hi, I would appreciate if someone could give me a confirmed answer. thanks in advance.

I am on DG30 (non-contract) and my bf is on digi prepaid.
he plans to change to DG50 (as principal Digi Family Line) while I plan to be his sub line, changing back to digi prepaid family. (coz most of the time I will be in singapore but I wish to keep the number)

the questions are:
1) do I need to change to prepaid first?
2) Can I pass my Sim card, photocopy of IC, authorisation letter to my bf so that he can complete the registration on my behalf? (this is bcoz I am in JB/SG and he is in KL, and we both cant be free on one particular day due to clashed and inflexible studying/working schedule)

Many thanks;)