The latest date that the next simultaneous Lower and Upper house election could be held is 24 May 2025.
I expect we'll know the answer around that date, but I've chosen to have this resolve much later on 1st of Jan 2026 to avoid any chance of confusion over dates.
I'll use the acting prime minister to resolve this, however I don't think that will change the result, since I'd expect that to usually be the prime minister proper, or someone from the same party.

"Other" will cover any edge cases not covered by the 2 main options.
This includes straightforward results like a 3rd party winning the election, but also more bizzare results, such as the government collapsing, or the title of "Prime Minister" changing.