Ms. Gita, first a few questions:
1) Are you the only child to your parents?
2) Do the properties that were purchased by your father have him as the only sole owner? In other words does he have sole absolute rights on the property OR has he bought it in joint ownership with your mother etc.
Now assuming that you are the only child and your father bought the property in only his name the following holds:
After death of your father, his spouse as well as all his children have equal rights on all the properties that are in his name regardless of whose money they were bought with. That makes you and your mother equal share holders. So if you are the only child then your mother can simply say that she wants to bequeath her share in the property to you. But mind it.... if she says ""50% of my share in ....property goes to.." it could well be taken to mean that only 50% of her share in the property she wants to bequeath to you...and not the 100% of HER SHARE...so what about the other 50% of her share??! Hope you get the point that I am trying to convey. So be careful with what words she puts in the Will....they should be crystal clear to avoid misinterpretations and hassles later. And I guess there is no harm in mentioning that those properties were purchased out of your money....Might be useful in fact in case of any issues that crop up in future.
Well that said....I am no legal expert.....but had such issues among my relatives...to help them out I researched and got some knowledge around there things. So this is just what I feel. But better to get a lawyers opinion. :) All the best.