I have figured out a method of inserting the next higher number from the items table sort field data into the insert form field "sort".
I set up a separate recordset with the following select query:
SELECT MAX(sort) +1 FROM items
And then bound the new recordset data to the insert form field "sort"
If it was a single record insert, it would be OK.
Unfortunately it puts the same number into all of the multiple record inserts repeated fields.
Therefore I need it to increment based on the number of repeat regions in the multiple insert records behavior.