Germanic and Balto-Slavic Cases in /m/

[Peter &/or Graham]

DLW suggested:   /bhi/ being added to the accusative (in /-m/)

This in itself would be an enormous innovation, which no other IE language
group shows for any of its cases.   (The only exception might be the
unproven development of the accusative plural from accusative singular +s).

So alas, even if true, (which it isn't), it would still remain "diagnostic".

Peter