I have 2 SharePoint lists:-
1) Master List with these fields:-
- ID
- Title
- Folio number
- initial order qty
- urgency level
- Part description
2) Vendor List with these fields:-
- Vendor
- Part Number
- Price
- SID (which should store the ID of the master).
now my screen looks as follow:-

where i need to have these 2 functionalities:-
1) when the user create a new item >> enter the master fields >> enter vendor fields >> click on "Add New" >> then new fields for the Vendor list should be shown >> so the user can add a master record and multiple vendor records on the same Save.
2) when the user edit the above form >> the related Vendor records should be shown..
so can anyone provide me with the details to implement this?
thanks