General :: Sorting Recordset In Form - Add Numerical Field With Sequential Value

I've been building a small app for some friends. At present, they enter "records" line by line into a word processor, then use (archaic, IMHO) macros to produce the desired printouts. They wanted the new data entry UI to mimic that process.

Ok, so I've adopted the datasheet form as the principal entry vehicle. Based on the initial info they gave me, there were two convenient fields to sort on, so I used them in the OrderBy clause of the query which serves as the form's recordsource. I also developed the code to maintain the sort order after they inserted or deleted a record.

Now it turns out they don't require an entry into those fields, and in fact there's no logical field at all on which to order by.

So the question is: how to approach this? From my reading, I can't use the primary key or an autonumbered field, since the former won't necessarily reflect the desired incrementation and the latter only triggers for a new record, not an insertion (is this correct?).

My thought is to add a simple numerical field (which will be hidden from the user) with sequential values. I can do the OrderBy on it, and add code to adjust those values whenever a record is deleted or inserted. (That will require looping through the recordset from the point where the deletion or insertion occurred.)

For instance, is there some way to add a calculated field to the recordsource for this purpose?