Maybe CraigDolphin can do a better job of describing the summary problem
The day I can ever do a better job with
anything to do with Access than you or Doc_Man is the day I take up skiing in hell
I take back my comment about nested iifs. You can avoid that easily enough as it turns out. To count files found in 3 fields of a table using a query might look something like Banana's example. Or for an alternative:
MyCount: iif([Field1] & "" = "",0,1) + iif([Field2] & "" = "",0,1) + iif([Field3] & "" = "",0,1)
Any time you add another field you need to add another + iif([Fieldx] & "" = "",0,1) bit to this query (and anywhere else you might do a count [eg forms, vba etc]).
By contrast, using a subtable the expression would be
MyCount: DCount("FileFieldName","ChildTableName","[TitleID]=" & [ParentTableName]![TitleID])
It never needs to be changed when additional files begin to be tracked.
Now what if you only want to count certain types of files? Say, ".doc"?
The solution with a child table setup is simple and future proof:
MyCount: DCount("FileFieldName","ChildTableName","[TitleID]=" & [ParentTableName]![TitleID] & " AND Right([FileFieldName],4)='.doc'")
Alternatively, the following would work but needs 'adding to' if ever more than 3 files are required.
MyCount: iif(Right(Nz([Field1],"Missing"),4)=".doc",0,1) + iif(Right(Nz([Field2],"Missing"),4)=".doc",0,1) + iif(Right(Nz([Field3],"Missing"),4)=".doc",0,1)
Lord help you if you forget to edit a counting function buried somewhere in your db app (maybe in a vba module, maybe a query) and calculations start going awry, totals start being off, and your PHB starts looking for someone to blame.
My experience over the last couple years has taught me one big lesson: whenever someone says there will only ever be a maximum of x do-hickeys they are probably lying.

They may not realize it yet, but there will come a day when they will arrive and ask for you to add 'just one more' type of do-hickey. This will probably not be the last time they do this.
For example, you are talking about a maximum of two required documents by current law and you are expecting one document=one file.
1. Laws can change. Do you really want to have to redo your app every time this happens?
2. Is it ever possible that one 'document' might be split into separate files? Eg, one document might arrive in two differing formats for different sections of the same 'document'. Maybe 'maindocument1.doc' and 'appendixAtomaindocument1.xls'. Or it might be broken into 'parts' because some file formats have a filesize limit (eg. mdb).
3. A future PHB decides he wants to track more than the legally rerqired types of documents. (Illegal warrantless wiretapping transcripts, for example

)