An explicitly plural form of "they", just like an explicitly plural form of "you" is "y'all".
Avoids the ambiguity of using "they" when referring to a group of people who include some people of non-binary or unknown/undisclosed gender, or when there's a group included.
In English, we often use a specifically gendered pronoun to refer to a specific member of a group, so we would say "Sally is doing something with Mike, but she'll be coming to the
party after." and it's clear that Sally is the one that
will be coming to the
party. If we said "he'll be", it would be clear that Mike was coming to the
party. And if we said "they
will be coming to the
party after", we would _probably_ mean that both of them were coming to the party, but it becomes a little
bit ambiguous.
"Th'all" solves this by always being all-inclusive. A
guy and a girl going shopping? Hopefully th'all find some good specials. A non-binary person and 3 dudes dressed fancy for a night out? Th'all look swanky.
The possessive form is "th'all's".
August and their partner Jim went apple-picking, but th'all
will be joining us later tonight.
Sarah and her coworkers are being overworked. Fortunately th'all are going to a union organization meeting on
Tuesday.
Michael Bloomberg and 14 other billionaires own most news agencies in the USA. Th'all have too much political power.