Hi there,
Don't worry about it. I had my mother in law deposit the whole sum in my account. No problem whatsoever. I don't have the documents I have provided with me right now. I'll look for them and if I find them will send them to you. But basically all you need is the following:
1- Have him/her put the cash in his/her bank account first.
2- Have him/her take the whole sum out of the bank and take a picture of the receipt that proves the money is his/her.
3- Deposit the same amount of money in your account and take a photo of the receipt that shows the amount of the money that was deposited (even if you deposited yourself, as I did, but it's better if the name of whoever is depositing the money figures out in the receipt).
4- Write a gift deed with his or her ID and bank account details.
5- Get it signed by both of you and then stamped in the town hall
6- Scan all these evidences, send them and you're good to go.
Hope this helps.