Karta giving an Interest-free loan to HUF can be considered a conflict of interest, and AO can put those income taxable in the hands of Karta.
Karta/Members can gift any amount they wish. It will be not taxable but must be shown in ITR as an exempt income.
There may be more technicalities around it.
PS: I am not a CA/Tax Expert. I would suggest you consult a good CA/Tax practitioner for such important financial planning.