Since the pandemic I have made a lot of recordings like this.
- Choose the biggest room in the house.
- Have the vocalists set up however, they are most comfortable. Seriously. Their comfort makes a way bigger difference to your recording than the 3% improvement you get from moving them in the best way for your mics and having them make a mistake or sing badly. Make sure they are happy/chill. Be relaxed. Tell them they sound great.
- They should be near the center of the room.
- Your cards and omnis should be about 5-6.5ft in front of them (my guess)...so the middle of the room is between them and the mics. I would guess mics are either either both in AB at 20", or cards halfway between AB and NOS. You don't want to point the cards too wide like you would in Carnegie Hall as here you will just get more wall reflection (ugh).
- Are you doing video/have to hide the mics? If not, and if the ceilings are high-ish, then put the mics 7.5' tall and angle them down a bit to face the singers' mouths. Bring the stands down if you want to get more drums (my guess is you won't want to).
-fyi this setup is basically the result of trying to compromise to get the mics close to the source so the direct sound dominates compared to wall bounce sound and floor bounce sound, but you don't want to close-mic a group as whoever is right in front will dominate too much.
It may help (maybe!) to have them with their backs to a *corner* of the room so you get less wall bounce from behind them back into your cards.
Really it depends a lot on the room, but this should get you started. OH and bring blankets for the floor between them and the mics!
Turn off the heat or A/C in the house. Your mics will pick it up if it's coming through vents. Also listen very closely because a lot of consumer electronics whine (lights, TV screensaver, etc. that you tune out in day to day life but no fun on your nice recording).