Possibly replacing my parents sky Q - advice please.

I'd suggest using a twin or quad LNB on the dish with an aerial input , that way you do not have to run another cable. You would then need a diplexer/sat uhf combiner at the tv end on one of the existing cables to give you saorview and satellite feeds.

Before I would consider an alternative solution for them, I would simple ask one question.

How easy would they adapt to a completely different system, particularly in terms of recording?

From experience, if they don't manage that 50 quid a month will seem like a bargain. Especially for your sanity.

Is it a bungalow or 2 story?

I wouldn't be climbing on any 2 story roofs to be honest unless I was completely comfortable doing so, and only with the right gear.

The dish is working with at least a dual LNB, so you don't have to touch that.

The aerial connection being in another room would suggest that was the TV room at one stage.

You need to test that connection, if it hasn't been used in years the aerial or cabling my have perished or depending how old it is, it may not have the right aerial.

Plug a TV into it and do a signal test.

If it works, running or rerouting that cable will be your main challenge, that depends on the layout of the house, if there is boxing, or channels, etc. Either splicing into or putting a splitter into the attic.

As for combi box, cheap and cheerful with very little options is what I would suggest.

https://www.freetv.ie/triple-tuner/

You need to find that cable so.

You had mentioned upfront cost as a factor TBF.

You can do loads of things. But the more devices you use, the more points of failure you potentially have.

For Enigma2. I'm a big fan of VU+, but you are getting into a different higher price band with them.

You cannot split satellite cables , at least not anything from Sky and certainly not legacy satellite gear like SkyHD.

The box sends various signals up to the LNB via those cables , so splitting them can send signals , some of them power , low power but still , to the wrong place = disaster.

You can split cables from a Unicable setup , but that involves all new gear , which is pretty hard to get these days as the Astra satellite only has until 2029 before its end of life.