Both rapid conscription and Relief are problematic and rather UP.
I would suggest to increase duration and to provide infatry with target size 1 that can merge but not reinforce so that the user can reinforce his front line unit.
Then one could even lose the whole take casualties first mechanism.
Both squads that are given via these abilities have got buffs to make them more attractive in the late game unlocked via teching so I don't think it's really an issue of viability, I agree with sander that it's a matter of finding the sweet spot of value/cost/timing.
Ostroppen are always fantastic for team weapons and cheaply holding ground and cons, while initially underwhelming /overpriced imo have never been better in the late game.
A little more utility for ostroppen might be enough but having 6 man lmg infantry that are cheaper than dirt with a snare is fantastic.
Also maybe finding a bit of a passive that attached to the ability might be good too, like cheaper or quicker reinforcement while active to get some value even if lucky (or unlucky?) and don't manage to take enough losses.