# Rearranging a simple algebraic expression

I have a polynomial of variables $$x,y$$, where $$|x|<1$$ and $$|y|<1$$. When I apply the Simplify function to this expression, I get an expression of the form

$$(x-1) (y-1)^3 y + x^n (x-a)^5 (y-b)^7 + ..$$, where $$|a| \geq 1$$ and $$|b| \geq 1$$.

Contrary, I want Mathematica to give me an expression of the form $$(1-x) (1-y)^3 y+ x^n (a-x)^5(y-b)^7 + ...$$

That is, I want in the simplified expression $$(a-x^n)$$ instead of $$(x^n-a)$$ and $$(b-y^n)$$ instead of $$(y^n-b)$$, if $$a$$, $$b$$ and $$n$$ are greater than or equal to $$1$$. Is there a way to do this by aiding a parameter/ an option to the Simplify or FullSimplify function? If not, is there any easy way to do it? I tried doing it with the replacement rule {(x + a_?NumericQ) :> (-(-a - x))}, but could not get the desired result.

Edit: Here is the Mathematica code for the expression I want to rewrite

(x - 1) (y - 1)^3 y + x^3 (x - 1)^5 (y - 2)^7 + x^3 (x^2 - 3) (y^3 - 3 )

and here is the desired result

(1 - x) (1 - y)^3 y + x^3 (1 - x)^5 (2 - y)^7 + x^3 (3 - x^2) (3 - y^3).