You have done wrong approach.RTI is not to issue certificate as to whether any documents is genuine or not. It is not the investigating agency. It is entrusted with work of  providing information as to any fact, and copy of original documents.

See the PIO can reject on third party ground though you can appeal the order to the First appellant authority stating that you need that for public good at large.

The Right to Information Act, 2005, contains several exemptions which enable public authorities to deny requests for information. ... Section 8(1)(j) provides protection to personal information of individuals from disclosure in the absence of larger public interest.

2) you can file appeal against said order before SIC 

A first appeal should be filed against this order. If they reject it too file a complaint in the state commission.

Regards 

Dear Sir,

You may prefer appeal and you may get justice only before Commissioner of RTI as following provision has given wide discretion and you can establish in your favor.

section 8 - 1(e) of RTI  Act. information available to a person in his fiduciary relationship, unless the competent authority is satisfied that the larger public interest warrants the disclosure of such information;

- As per Section 8(1) of RTI Act,2005  , there shall be no obligation to give any citizen information which relates to personal information the disclosure of which has no relationship to any public activity or interest . 

- Hence, it rightly rejected , as the genuniess of educational certificate containing mark sheet of others ,cannot be disclosed by the act.

- If you are not satisfied with their response, then you can file an Appeal under section 19 of the RTI act.

The ground of rejection is not legally tenable and else you have the option of preferring an appeal  before the departmental appellant authority.

Thereafter the second appeal lies before the Information Commissioner. 

Section 8(1)(e) in The Right To Information Act, 2005

(e) information available to a person in his fiduciary relationship, unless the competent authority is satisfied that the larger public interest warrants the disclosure of such information. 

If the first appellant authority has rejected then you have to file Second Appeal Information Commission enclosing copy of all previous communications or you can also meet chief information commisioner  and raise the matter before him.

If you are not satisfied with the reply you can file a first appeal against the said order of RTI

Hello,

You can file an appeal challenging the same .

Regards

Dear Sir,

Section 8(1)(d) requires that such information should not be disclosed unless the competent authority is satisfied that larger public interest warrants the disclosure of such information

Are officials required to give information about themselves and their families under the law? Can the public request this kind of information? Should it be given?

Officials are not required to provide private or personal information which is exempted under Section 8(1) (j) of the Act. Again, this must be decided on a case to case basis (as has indeed been the case with the decisions of the CIC). If public interest is served by disclosing such information then it must be given.

Third party information may not be provided under RTI.  Can try by filling appeal.

You can file application before first appellate authority under RTI act. 

Or you can change your query and ask for details of mark list of that complete batch. 

If you are not satisfied with the decision given to you then you may prefer an appeal against the decision on this.