This is my response to you:
1. If the shop was solely under the name of your grandmother then every legal heirs of hers will get a share;
2. If she never made a Will then all the legal heirs get an equal share;
3. So you being the legal heir of your father, you and your mother and your siblings will get his 1/3rd share and other 1/3rd each will be divided between your uncles;
4. Regarding your property, if it is ancestral (since you mentioned it is a mansion) then everybody in the family tree gets a share;
5. If it is solely your grandmother self-acquired property then all her legal heirs i.e. Class I legal heirs will get the share;
6. It is advisable that you engage services of a lawyer and show him/her the papers, do the title search of the property, and then you can get a clear idea of the share in the properties.