Q:

Will an Egg move still be passed on if it is overwritten by the daycare's levelling?

I'm trying to pass on the move Wish to a line of Eevees, as well as get the right nature and IVs. The Smeargle I used to pass on the move only has 1 IV, and I'd like to swap in another Eevee (one of the children which has Wish) that has 3 IVs. 
However unlike Smeargle, Eevee learns a lot of moves, so I'll only get 5 or so Eggs before that Eevee forgets Wish, due to the daycare's feature of erasing old moves in favour of new.
So my question is, do I need to take out that Eevee periodically to re-teach Wish? (At the cost of a heart scale) Or will its moveset stay the same until its withdrawn, therefore continuing to pass on Wish anyway?

A:

AFAIK as long as you do not take out the Eevee from the day care, it will continue to pass on Wish to its children. So if you are just keeping it in there to make a lot of Eevees, it will serve its purpose.
If you really want to keep wish on it, then you can remove it periodically from the daycare and rearrange the moves it has learned, so that Wish ends up at the bottom. The moves will be learnt by deleting ones from the top and adding a move to the bottom of the move list. This will give you a chance to keep wish on the Eevee while it is leveling and learning moves in the daycare. (You have a window of 3 move learns before you rearrange or else you will lose Wish)
If by chance you end up losing Wish then you have to go to the move re-learner and pony up a Heart Scale.
PS: I bred Stealth Rock onto my Tyranitar(Larvitars) this way. So I know it works out better and takes very little effort on your part.

