I remember your recordings from another thread - the quartet sounded fine. I feel you know what you want and have an ear for it... If you will hire someone - you need to hire someone really good or you'll be very likely frustrated, since you could do it better...
So yes, as others suggested - outside help would be easier - I don't know your budget considerations, etc. but it will be difficult if you play in different groups AND record - also because of the time... I know it can be done, but seems difficult in your case.
For positioning - I would use the nice window background of that weird space - I don't know how it sounds - but would probably place the musicians so that it looks cool in that space - use the interesting background, natural back light and also front light, would probably try to hide the mics, but if it's also for the album, focus on sound first, video second... (if the performance and sound is nice, I don't care if I see messy cables and mics and stands)
From your examples in another thread - you tend to record fairly close, but it was effective, so don't digress from that approach that you already know (and like) - NOS or ORTF in a nice close(ish) position - either pair of your mics would work - for the bigger group - I'd use a Big AB + small AB (or ORTF/NOS) main pair... if that is all that is available...
Actually I would do the same for the other set ups - quartet, etc. Combine close small AB (CM4 ca.30 cm apart, slightly angled out) or in ORTF/NOS and Big AB (some 4m apart and high and some 2 - 3m meters in front of the group) - use the latter to add "dimension" and mix it in to taste - watch out that it doesn't mess up the phase or smear too much... I wouldn't use CM4 for the Big AB - too much noise. Telefunken M60 would be good... some nice omnis would be probably better... especially for the group with double bass...
If you want to read more about the small AB and big AB approach - you can check this (Tritonus use a combination of a pair of Neumanns KM143 close in small spaced AB and Big AB of B+K4006 for string quartets):
https://nimetu.org/a-small-workshop-...arkus-heiland/
My own application of this approach:
https://samply.app/player/vb4o0tfiaz1bNvcCzDwt
And you can see Markus Heiland's set up for Danish String Quartet here:
https://youtu.be/FOjdoM27Wd8?si=b0WufPrHlAdTRajP&t=54
(you only see the stands of Big AB and the mic stand with another pair facing the wall that you can see in the video, is very likely an alternate stereo pair that was not used and was just put aside; from his words, they used only Small AB and Big AB)
When you start - check the recording including your part, before doing more takes... the balance might be different than without you - probably not much, but still...
I just did such a DIY session with my collegue, double bass player - but ours is a simple duo setup and we had the luxury of two full days of having a church for ourselves. We set up everything, gain staged, checked the sound from his solo playing, then recorded a few different test recordings of both of us that we listened to, did small mic placement adjustments and started recording. Turned out well and very likely better than most of the available local outside "help" would do - because we know what we want and know how to do it to an extent...
A solo double bass and solo "Sanctus bells" from that session - we haven't decided, yet, on which takes to use from the duo recordings (double bass is "small AB (M221 omnis) plus Big AB" (MKH20 omnis) approach, because the percussion mics were muted for this video - no EQ and reverb is only natural from the church):
https://www.youtube.com/watch?v=QLdgEzp9WMk
https://www.youtube.com/watch?v=NPOjA454gXg
But I can't imagine being a part of a larger group and at the same time recording it myself, though. It would be too hectic and too complex for me...
Good luck! I think you can do it well, but it will be difficult for you. (pssst, hire Earcatcher)