You can choose the caste of either of your parents.

If you want to choose your father's caste, there is no restriction for it. 

The child gets the father cast. Caste is determined by birth, and a Child can get the caste of the father irrespective of the caste of the mother.

The fresh circular, adopted on guidelines of the Union government directs the collectors and directors social justice department to issue SC and ST certificates to children of women from these communities, who are separated, divorced or single mothers.

This is a marked deviation from the practice of of granting caste certificates on the basis of the father's caste.

It seems that you are facing a difficulty in claiming your caste as SC converted Christian. This is a complex issue that involves the interplay of religion, caste, and reservation in India.

The legal matters related to the SC converted Christian caste are governed by the Constitution (Scheduled Castes) Order, 1950, the Constitution (Scheduled Castes) Order (Amendment) Act, 1990, and the Constitution (Scheduled Castes) Order (Second Amendment) Act, 2002. These laws specify the castes and communities that are recognized as Scheduled Castes (SC) for the purpose of reservation in public services and educational institutions under Article 341 of the Constitution of India. These laws also exclude persons who profess a religion different from Hinduism, Sikhism, or Buddhism from the SC category

Some of the points that you should know about the SC converted Christian caste are:

• The SC converted Christian caste is a term used to describe persons who belong to castes that are listed as SCs under the Constitution (Scheduled Castes) Order, 1950, but have converted to Christianity from Hinduism, Sikhism, or Buddhism. These persons are not eligible for reservation benefits as SCs under the Constitution.
• The SC converted Christian caste is different from the Dalit Christian caste, which is a term used to describe persons who belong to castes that are not listed as SCs under the Constitution (Scheduled Castes) Order, 1950, but have converted to Christianity from Hinduism, Sikhism, or Buddhism. These persons are also not eligible for reservation benefits as SCs under the Constitution.
• The SC converted Christian caste is also different from the Latin Catholic caste, which is a term used to describe persons who belong to castes that are listed as Other Backward Classes (OBCs) under the National Commission for Backward Classes Act, 1993. These persons are eligible for reservation benefits as OBCs under the Constitution.
• The SC converted Christian caste has been demanding for inclusion in the SC category for a long time, citing historical and social reasons. They have argued that they face double discrimination on the basis of religion and caste, and that their conversion has not changed their socio-economic status. They have also challenged the constitutional validity of the exclusion clause in the Constitution (Scheduled Castes) Order, 1950 before various courts and commissions .
• The government has been opposing the demand for inclusion of SC converted Christians in the SC category, citing legal and policy reasons. They have argued that religion and caste are distinct concepts, and that conversion implies a change of identity and affiliation. They have also argued that inclusion of SC converted Christians in the SC category would violate the principle of secularism and affect the rights of other SCs .

Based on these points, I can try to answer your queries as follows:

• You cannot get SC converted Christian as your caste under the current legal framework, as you are not eligible for reservation benefits as an SC under the Constitution. Your father’s re-conversion to Hinduism may not affect your status as an SC converted Christian, as it depends on your own profession of faith. Your mother’s Latin Catholic caste may also not affect your status as an SC converted Christian, as it depends on your own birth and descent.
• You may have taken your caste as SC converted Christian till date based on your family history and social identity. However, this may not be legally valid or acceptable for official purposes such as admission or employment. You may have to face legal issues if you claim reservation benefits as an SC based on your caste certificate or declaration.
• You may not be able to get an SC converted Christian claim under the current legal framework, as there is no provision for granting reservation benefits to SC converted Christians under the Constitution. However, you may be able to get some benefits under the OBC category if your caste is listed as an OBC by the state or central government.
• You may also be able to pursue your legal challenge against the exclusion clause in the Constitution (Scheduled Castes) Order, 1950 before the Supreme Court or other competent authorities. However, this may take a long time and involve a lot of litigation and uncertainty.

Scheduled Caste converts to Christianity and Islam are not eligible for consideration as persons belonging to the scheduled category.

you can take father’s caste in the same but can’t bounce back to mothers for facility in SC

Caste assume with the birth of child and not conversion. Since your father is SC, you will also consider SC. 

Greetings of the Day,

I have read your issue but find that there are some facts which need to be clarified. You can approach on either nine two one two one two four five eight five or seven zero four two eight three three six eight six for personal approach.

We Hope that a personal consultation would be fruitful to the issue and it would be better for you to talk to someone directly.

Best Regards

SPS Law Chambers
New Delhi.

Dear client,  

Caste and community categorizations can be complex and are subject to specific laws and regulations in India, which can vary from state to state. It's essential to consult with a legal expert or authority on caste and community matters in your specific region for precise guidance.

In general, caste and community claims are often based on the customs and laws of the particular state or region you are in. The eligibility for claiming a particular caste or community status may depend on factors such as your family's history, your own religious conversion, and local laws.

Dear sir, 

In the state of kerala you can get the the SC converted christian claim as that of grandfather.