Comment on BTST/ATST( Buy/Acquire Today Sell tomorrow)
1. Yes, she can.
2. BTST is when you buy on Monday and sell on Tuesday. If you receive delivery of the shares that you purchased on Monday, you can sell the same on Friday with no risk of auction.
3. It would depend on your trading activity. Here’s more on it to read: http://zerodha.com/varsity/chapter/classifying-your-market-activity/
4. It’s a risk you have to take, It’s similar to asking ‘Can I share my debit card and ATM Pin with my relative?’. You’ll have to do it at your own risk. There aren’t any legal implications as such since you’re sharing them voluntarily.