Transitioning from UK Tier 5 to UK Tier 2 visa whilst residing in Republic of Ireland [closed]

I have arrived in the Republic of Ireland whilst holding a UK Tier 5 visa which I haven’t used. It expires 8th June 2022 and the vignette is valid until then.

I am getting a Tier 2 UK visa by a hospital and they’ve let me know that I need to activate my Tier 5 then stay in the UK until my tier 2 has been processed.

I’m wondering if I go to Northern Ireland from the Republic of Ireland how my Tier 5 will be activated as there is no border control. I’m also wondering if my application is lodged while I’m in Belfast if I can return to RoI to await the outcome (again because there is no border control)