Espagnolette or equivalent locks to old uPVC windows

It can be done depending on the profile of the system that has been used to make the windows. There’s a company in Coolock that supplies aftermarket window and door accessories. Unfortunately they can’t be mentioned here but you can google them.

Mila dot ie

no links, i'm new.

Ebay is great also,

Check the ones with the most buyers, let other do your research ;-)