You may be able to run

SELECT @@IDENTITY FROM MyTable;
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and pass that through to the underlying table. I found it by googling for MS Access and last insert id. One would think the DBD::ODBC documentation should help too, but I found it a bit opaque on this topic. In many advanced SQL dialects you can also say something like

INSERT INTO MyTable (x,y) VALUES (1,2) RETURNING rowid;
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Then retrieve the rowid by fetching from the statement handle, if the DBI driver permits this.

HTH,
SSF