Question:How to rewrite my expression in a more compact form?

Question:How to rewrite my expression in a more compact form?

Maple

I have an expression Z_val which I would like to rewrite in a compact, more readable form. Assuming that simplify() did its job, I thought of using (1) alias(), and (2) eval() with some combination of my parameters, since such combination occurs repetitively in my expression.

(1) is not particularly useful for my problem at hand. In particular, powers are not recognized and the alias I defined did not substitute the combination in all the places I was expecting to.

(2) is somehow effective but my expression becomes arguably even more complicated.

What else would you suggest?

EDIT:
 > restart;
 > local gamma;
 (1)
 > M := -lambda*(beta^2*(sigma__v^2+sigma__e^2)+alpha*sigma__d^2*(alpha+1))+beta*sigma__v^2; V := simplify((1+(Cov__XY/(sigma__X*sigma__Y))^2)*(sigma__X*sigma__Y)^2);
 (2)

# Specify the terms, calculated by hand

 > sigma__X := beta^2*(sigma__v^2+sigma__e^2)+alpha^2*sigma__d^2; sigma__Y := lambda^2*(beta^2*(sigma__v^2+sigma__e^2)+sigma__d^2*(alpha+1)^2)+sigma__v^2*(1-2*lambda*beta); Cov__XY := M;
 (3)
 > V;
 (4)
 > Z := M-(gamma/2)*V;
 (5)

# Specify lambda, beta, and alpha

 > l := simplify(-gamma*sigma__e^2*sigma__v^2/(2*(sigma__e^2 + sigma__v^2)) + sigma__v^2*sqrt(gamma^2*sigma__d^2*sigma__e^4 + 4*sigma__e^2 + 4*sigma__v^2)/(2*(sigma__e^2 + sigma__v^2)*sigma__d)); b := simplify(eval(sigma__v^2/((gamma*sigma__e^2 + 2*lambda)*sigma__v^2 + 2*lambda*sigma__e^2), lambda = l)); a := simplify(eval(-lambda*(sigma__e^2 + sigma__v^2)/((gamma*sigma__v^2 + 2*lambda)*sigma__e^2 + 2*lambda*sigma__v^2), lambda = l));
 (6)
 > Z_val := simplify(eval(Z, [lambda = l, beta = b, alpha = a]));
 (7)
 > eval(Z_val, gamma = Gamma/sigma__e/sigma__d);
 (8)