Soooo Skeets, you want 28mm Seminole women in those full-length, long-sleeved dresses decorated with ruffles and ribbon applique, and non-warrior men in those long decorated shirts. And children. And some white folks too. Cheese whiz.
For men, pick a suitable warrior figure, trim his weapons off and bend his arms and legs until he looks more peaceful-like. Really, that will probably be easier than finding a suitable figure sculpted to the purpose.
There are a couple of the old Rafm Flint & Feather figures I like to use for this kind of conversion, because they're sculpted open-handed with no weapons, and it's relatively easy to reposition their arms, legs and heads by bending them. It's easy to add a blanket or a breech-clout cut from cigarette paper and dipped in epoxy before applying it. Be warned that these are small, 'true 25mm' figures and won't match new 28mm figures in stature. But you can at least use them as teenager boys:
link
link
The old man and woman from the Conquest Iroquois Ritualists set might be painted to work as elders:
link
There are three women in the Dixon Apaches line. I'm sure (because I own a few) that AP09 is dressed in Mexican style long-sleeved blouse and long skirt over boot moccasins, with long, loose hair. I'm not sure, but think AP08 and AP10 are in the same style (unfortunately, these figs aren't illustrated in the catalog). You could paint as much ribbon applique on these gals as you can stand, and cover up the feet with flocking:
link
Dixon Wild West civilians might also be useful for white wimmin and chirren, although the Dixon women are all armed and belligerent. They're down around WG31 on this list:
link
Children often ran more-or-less naked in Florida. Still do, I believe. I picked up a pack of 15mm Museum Miniatures nude women with swords, carved off the swords and filed their boobies down, and I have some naked little girls for my 25mm collection. I made similar use of a pack of 15mm Museum Miniatures nude male archers. They were bald, so I added top-knots of hair with modelling putty. Little boys often played with bows and arrows, right?
I've also scrounged archers in breech-clout and moccasins from several sets of 1/72 plastic Indians. I got some from the Airfix set, some from the Imex Sioux box. I trimmed off any feathers or other inappropriate detail. Looks like there might be some useful figures in the Pegasus 1/72 Mission Indians box, possibly some women in dresses who you could use as young girls:
auction
Good luck.