Spawning Dempseys

My Demseys have spawned again after losing all their fry (they never made
it to free swimmimg) about two weeks ago.

My attempt at a divider was useless as the fish were able to push past it.
The Depseys did their best but overall conditions conspired against them
and all the fry were eventually lost.

I actually think a great dela of the fry were lost through the gaps of the
UGF plates ( I am not actually using UGF but just have the plates to keep
the rocks off the glass bottom). This was becasue as soon as the fry
became wigglers the mother sucked them off the rock and spit them into a
pit she had dug which exposed the paltes.

I want to try and avoid this and save some fry in the tank. I will be
getting an egg crate divider this time.

I would like to know if it is feasible to rearrange half the tank by
taking out all the rocks, removing the gravel (5mm silica sand) and
removing the plates and then replacing everything. Most of the eggs have
been laid small easy to handle rock which I could just move to one side.

Will the parents be scared off the eggs if I do this? I don't want the fry
as much as I want to see the parents raise them so moving all eggs to a
separate tank is not the solution.

Maybe I could fill in all the pits just enough to cover the ugf plates
before the mother satrts moving the fry so at least they
won't fall through the cracks.

Any other ideas.

Thanks

Trev