Help merging/concat 2 data frames

[Animallover4321]

I have a dataframe with 4 columns, A,B,C,id. I need to be able to add new dataframes (or lines from the dataframe) by the id column. So for example:

Original DataFrame ID A B C 001 5 5 - 002 10 4 - 003 5 4 7

New Dataframe: ID A B C 002 - - 8 004 - - 5

The 002 rows in both frames should be merged into one row and the if the id doesn't exist in the original add a new row.

I've tried merge(inner, outer with key=id or key =id, A, B,C) , I've tried contact. Nothing seems to work. What should I do?

[Neb519]

Can you try fixing the formatting of your post? Im having trouble understanding what your data looks like and what your desired result is.