On Sun, 9 Aug 2020 08:15:08 +0100, "Brian Gaff \(Sofa\)"
wrote:

This is one of those instances where (for most of us anyway) 'a
picture speaks 1000 words'.

Not that you couldn't describe the scenario to some degree but you
would have to also describe the loads and stresses likely in the
completed chair to predict the likely result.

Cheers, T i m

Yes if the casting is quite thick and is not suffering the porosity issue, a
couple of self tapping screws in a brace on the hidden side might help with
strength, ideally an angled section.
Brian