Is there any way to lace a 28 hole hub to a 48 hole rim??
Of course you can do that!
...there will be un-used holes in the rim, in the end, and an irregular spoke pattern.
Just lace from the hub in a normal fashion, and select the best balance you are able to on the rim side of things.
I AIN'T NO EXPERT... lol
....but I recall when I was a kid... (difficult anymore) folks would lace up what we called 'funny wheels' that were egg shaped and ride their bike in parades on holidays. They gave an entertaining up and down motion to the bike that was most fun at low speed.
SO...
If they could do THAT,
You could fab a mismatched count in a concentric circle.
Just do NOT count on it being optimal for strength and appearance!
Best
rc