Gift deed: When to prepare - End of FY or as soon as executed or can it be past dated?

Dear Sir/Madam, My query is on Gift deed. Son transfers Rs 1 lakh every 2 months to his Mom as gift. 

1. When should this gift deed be prepared - every quarter, every year in March (end of FY) OR can he prepare gift deeds now for FY 2020 till date (past dated)?

2. In FY2021-22, he transferred Rs 8 lakh to his Mom. But in the same year Mom transferred back 6Lakh to him as he was in need of money. Now while filing ITR, will Mom declare 6Lakh or 8 lakh as amount received as Gift?

Thanks in advance, 

Pret