Use of parentheses to include both singular and/or plural possessive

Question

GIVEN: "You can either pay for, or rent, your kid's baseball uniform."

QUESTION: If you are sending form letters to each of a number of parents, some of whom have 1 child, and others, 2 or more children, who will be playing ball, could you write:

EX.1. "You can either pay for, or rent, your kid's(s')baseball uniform(s)."

[I read the suggested "Questions that may already have your answer," above, which don't seem to pertain to the present query, and researched 's(s') online; and, so far, I haven't found anything on this. I compared my question to the questions and answers, here: How do you make a word like "parent(s)" possessive? and thought that nothing there adequately answers it.]

UPDATE: @Davo's answer, below, is clearly a way to express what is intended. I'm asking whether or not the 's(s') construction would be correct/ understood.

Answer 1

The question misses the point twice. Properly, parents have children or kids in this case. A parent might have a child or in this case a kid and to whom is your form addressed, please?

Is it addressed to Dear Parent or Dear Parents or Dear Mr and Mrs (Name from Database) or whom?

The simplest solution would be to use Dear Parents and match that with kids and uniforms… which will mean making it obvious in the first sentence that Dear Parents is a generic term, not something single parents might find insulting… so perhaps Dear Parents, We’re asking all of you…

The toughest method would be to try to match Dear Parent, Dear Mr, Dear Mrs or Dear Ms. If you could extract individual names from students records, how exactly would you decide whether Mr or Mrs was the ‘main’ parent?

Secondly, that looks like a letter from a school, or a little-league baseball club which almost by definition, has easy access to the facilities of prolly several local schools, not to mention several parents’ offices…

That means significant numbers of supporters should have access to MS Word or other modern word processors, any of which could easily cope with personalising everything you mentioned.