1. The property of your Aunt will go to you as per her WILL.
2. However, the question remains whether the WILL can be given effect to in Haryana without first getting Probate of the WILL. I understand that Probate of WILL is not required in Haryana. Please have this checked up with local lawyers.
3. If probata of WILL is required, get the probate by approaching appropriate civil court.
4. In case, Probate of WILL is not required, then you may have to first obtain a Legal Heir certificate from the Tehasildar Office of your locality.
5. The Legal Heir Certificate is to be obtained separately for your Aunt and your father.
6. As Your Aunt was unmarried, according to Section 15(1) (d) of Hindu Succession Act, 1956, her property will go by way of inheritence (in case she had died intestate i.e. withou making any WILL), upon the heirs of her father.
7. You and your siblings being the heirs of your Aunt's father. On this basis, you have to obtain the legal heir certificate.
8. Having obtained the legal heir certificate, you have to obtain No Objection Certificate from your siblings stating that they have NO OBJECTION if the property of your Aunt is transferred in your name.
9. In respect of the share of your father in the property, your siblings have to give REGISTERED RELINQUISHMENT DEED, relfinquishing their right, title, share and interest in the property of your father and relinquishing the same in your favour. THIS DEED HAS TO BE REGISTERED. Otherwise it has no legal validity.
10. Based on the WILL + NOC mentioned at 8 above, and the legal heir certificate obtained in respect of your Aunt, you can make an application to the Municipal Authorities to mutate the share of your Aunt in the property in your name.
11. Similarly, based on the Registered Relinquishment Deed from all the other legal heirs (i.e. your siblings) of your father, please make an application to the Municipal Authorities to mutate your father'share in the property in your name.
12. Once mutation has been effected as at point 10 and 11, you will become the absolute owner of the entire property. YOU HAVE TO ALWAYS RETAIN (1) the Original WILL from your Aunt, (2) the copy of the Legal Heir Certificate granted in respect of your Aunt; (3) copy of the NOC granted by your siblings and (4) the Mutation granted by the authority. All these combined will be the proof for your absolute ownership of the property of your Aunt.
13. Similarly, you have to retain (1) the Original Property papers on the basis of which you say that your Aunt and your Father are the owners of the property; (2) Original Relinquishment Deed granted by your siblings and (3) the Mutation granted by the authority. All these combined will be the proof for your absolute ownership of the property of your Father.
14. Please note, that there will not be any single document which will specifically show your name as the absolute owner of the property. (ONLY THOSE DOCUMENTS MENTIONED AT POINT 12 AND 13 will prove your absolute ownership)