I've never posted on these forums before. I am going to try to spell out my goal and see if someone can help. Basically I am trying to chain together assignments of deeds of trust (DTs), where one mortgage holder sells (or assigns) the mortgage to another and then another and so on. This goes on several times over for each DT, one DT could be assigned or sold 50 times, and each assignment may contain and assign 500 DTs.
Sheet 1, Column B, I have a list of Instrument #s of the DT. Basically the file numbers from the county clerk/recorder office.
Sheet 4 contains a spreadsheet that lists the Instrument #s of Assignments of DTs in col E, and col I contains the DT instrument # that that Assignment assigns, which are the same DTs listed on Sheet 1 Col B. There are several assignments for each DT, and again each assignment lists several DTs. So there may be 100 rows on Sheet 4 that contain the same instrument # in col E. And there will be duplicates in col I because the DT is affected by more than one assignment.
Back on Sheet 1, in columns C,D,E,......, I want to list the assignment instrument #s next to the DT instrument numbers. I want to list every assignment that affects that DT. I could use Index/Match, but there would be multiple results. Which does index/match decide to display? I assume the first one it hits. These instrument #s increase. So the instrument # from an Assignment filed yesterday would be lower than an instruments # of a filing done today. So I would like index/match to pick the smallest instrument # for column C, then the next smallest for column D, and so on, increasing as we go.

I hope I am explaining that well.

Also concerning index/match, let's say I set column C as follows and it returns one, but obviously not all, matches.
=index(Sheet4!D:D,(match(Sheet1!B10,Sheet4!I:I,0)))
Now when I filter by any other column, the cells change. Some return an #N/A and others return a incorrect value, though it was correct before the filter.

Any help would be greatly appreciated. Please let me know if you have any questions and what I more need to explain. Thank you for your time.