How to copy data from non-depending part of excel table to refreshed monthly table...

How can I copy data from non-depending part of excel table to refreshed monthly table so it keeps the names in the same row as original?

Hello! I'm a brand new member of this community and I found it the best suited to answer my excel-related question.

My problem is the following:

I got a monthly updated table with client names in two (in my case I and J) columns. This, main part of the table, which is prepared by our main office, spreads from column A to AB;
there is, hovewer, a second part of the table, which is separately prepared. It contains columns from AD to AJ, of which the first two (AD and AE) are of my main concern here, and the rest are about some dates (AF and AG), meeting results (AH and AI, merged) and additional notes (AJ). A person in charge should enter a client's name into column AD and his/her surname into column AE, accordingly.

Now coming to the point - The names in columns AD and AE should always match the rows where the name we need to enter (only SOME names from the left table are entered) are originally placed in columns I and J. For the reference sake - there are approx +1700 names listed there (in columns I and J) in an average monthly table, and of those, only some 50-100 names we use to work with in right (separately prepared) table.

So, basically, we enter names (manually or c/p) into right column when we need some particular client - we find where they match a particular row left (from columns I and J) and then we enter them in the SAME row on the right.

The problem arises, however, every time an updated table comes into power - many more rows are added then, a few are deleted.

My question is therefore: how to keep all the names already entered into right (non-dependent of the left one) part of the table, so they still match the exact row where they have been entered a previous month, along with all other entered data in neighboring cells? I suppose it should involve playing around with lookup, index and/or match functions so I tried it for some time, but without satisfying results.

I'd be very grateful if you could help me to get closer to solution. I hope I've been clear enough about the issue; I'll gladly clarify further if needed.
Thanks.