sister in law has to execute POA in your favour 

2) it has to be duly stamped and registered as she is empowering you to sell her share in flat 

3) it will attract high stamp duty as you are not close blood relatives 

1. The POA to be relied upon to sell the fat on behalf of your sister in law must be registered one.

2. If your SIL is ordinary resident of Mumbai then POA registered therein can be relied on on in MT Abu.

3. At the time of registration of POA physical presence of both you and your SIL is mandatory.

4. the cost of an advocate can not be predicted.

In most states stamp duty for POA is minimal . In WB it is Rs.50/-.

The time taken to make this should not be more than 5-7 days.

POA should not take more than a week 

2) details of property should be mentioned in POA 

3) since sister in law is authorising you to sell the property POA registration is mandatory 

1.  POA for immovable property in Mumbai, must be stamped (500/-) and registered before the local Registrar of Sub-Assurances in Mumbai, for it to be legally effective.

2.  Stamp Duty of POA is separate and Stamp Duty on Sale Agreement is separate.

power of attorney given to sell immovable properties should be registered.

If the POA is executed between blood relatives no stamp duty required. 

physical presence of both of you is mandatory. 

You need to be present for signing and registration. It's drafting is quick registration takes time. You need to pay the applicable stamp duty for the same in case of execution of POA

Notorised GPA valid all over India, will execute on 500/100rs stamp and max. 100rs notary charges. Single day thing. Your presence is necessary to accept it, but she can sign on your behalf if you authorize her. 

No document need to execute POA.

NO stamp duty but non judicial stamp paper.

Yes you have to be there for registering a power of attorney in bombay, or it can be notarized also.

Further it won't cost much just the general drafting fee registration fee.

See the property documents should be in your names.

It will take 2 to 3 days.

In POA also duty is applicable .

This is my response to you:

1. You will have to execute and register the POA;

2. The same will require payment of stamp duty;

3. You will need to state further facts of your case;

4. Did you obtain letters of administration?

5. Consult a local lawyer and take steps.

You have to register the power of attorney with proper stamp duty and registration fee and stamp duty varies from state to state.

Your presence is not necessary at time of registration of power of attorney but it is better if you will also sign the POA at time of registration.

You can take a POA deed in your favor to sell the property on her behalf too.

You may have to be present before the registrar to get the POA deed registered on your name.

The cost and expenses may be enquired from the lawyer you may engage.

The POA deed can be registered on the same day.

You will be informed about the documents that are required to be produced before the registrar for registering the deed by the deed writer on the spot.

1. As per the information mentioned in the present query, makes it clear that she wants to execute the POA in your favour so that you can sell the flat as she also has the share in the same.
2. Yes, you can do it and yes you have to get it executed at the place where she has been right now.
3. It won’t cost much, drafting of POA would cost almost 5K and registration charges will be in 2 to 3 K.
4. And stamp duty is to be paid at the time of selling the flat not for the execution of the POA.