Maps :Multiple record to single record

I have a source schema with multiple records(but not the same structure), need to map the fields in these records to a single record, could anybody give me some idea how to do that? I try to use looping functoid but it seems only for multiple repeat records with the same structure.

Source Destination

Root Root
Record1 Record
item1 ————> item_a

Record2
item3 ————> item_d
item4 ————> item_e

I did try it with looping functoid, only output the one item in the first record, all the others are missing…… Please help me out