I'm very surprised that the positions and interests of current union members, retired union members, and future (union? remains to be seen) employees are even spoken of as if there were some commonality.
In point of fact, unity of representation among these three disparate groups is an extra-legal fiction dating from Roosevelt in which a union's ability to bargain (viz. yield to coercion, and accept bribes) and thereby resolve a crisis was correctly evaluated as badly compromised and delayed if retired members (and the equivalent of a guardian ad litem for future employees) were permitted separate standing.
The interests of retired employees is adverse to that of current employees, and only in "special cases" (politically sensitive issues, where favors and power trump the letter of the law and existing precedent) can they be remotely considered as united in interest.
Unions invariably throw retirees and future hires under the bus before relinquishing $1 of current pay and work rules, since retirees (in large part) do not vote, and future hires are not represented at all. This latter practice is called "f*cking the unborn", in which the starting salary and raises by seniority (increments) of new hires are far below existing. 30 years of "hired in 2010" will not equal 20 years of "hired in 2000", etc. No one cares - as long as there's no strike, and the union subsidizes Democratic candidates.