Maybe a 'ordering' system to request troops recruitment at a NPC, you pay the NPC and then do your thing. When you return, X amount of soldiers will be available in the menus to recruit immediately.
A donation system in the game might work to 'donate' high leveled troops in return for special currency as you are changing contracts. Because owning dozens of level 20 soldiers may drain your gold early on, so for these players, donating their soldiers to a city to be recruited by someone else would be a better utilization than 'dumping' them by kicking them off the squad. You can only donate soldiers in demand by players to be paid basically, so buyers has to pay a bonus fee to order soldiers which goes to the person donating it.
It can also be like a mercenary system maybe...
Example:
If I request 50 Imperial Trained Infantry, I would need to pay a fee of 180 gold per soldier first as a deposit.
If someone dumps 25 Imperial Trained Infantry into the system, they get 160 Gold (20 gold is the administration fee) per soldier.
I can't collect all 50 soldiers from the NPC (Maybe a Garrison Steward) until I have space in my squad, and the contract is fulfilled by other players to provide 50 soldiers.
So if there is 49 / 50 soldiers in limbo, there will not be any wage to account for as they operate as militia for the garrison temporarily until the contract is fulfilled and the buyer comes to collect the soldiers.
Of course this idea is moot if players simply 'trade' soldiers like trading goods and can haggle each other online for the price, but the system can be utilize for other forms of soldier transfers, especially if you wish to recruit soldiers for a estate or castle or such to act as a militia.
