Upradeable but non-purchaseable units?

[GaryChildress]

Trying to figure out if there is a way to do this:

I want core units to be upgradeable but not purchasable. Trying to create a campaign where the player starts out with a set of core units that he has to use through the entire campaign. He can upgrade the units to better ones as time goes on, however he cannot use his points to buy new ones.

Is there a way to do this?

Thanks.

[ThvN]

I assume you want the upgrades to be unavailble for purchase as well? Normally, the trait 'nopurchase' makes a unit unavailable to purchase but when given to the player through a scenario it can be added to the core and upgraded normally (but see below). It is the same system as the 'captured' units in the Grand Campaigns.

The tricky part is upgrading a unit to a 'nopurchase' unit. I don't think that is possible without cheats, except for 'bonus' (SE) units.

So, I'm thinking, a method that could work would be to give a player no SE slots (or just less than the size of the core, to prevent receiving them randomly) and start with a core with troops which all have the 'bonus' trait. These can be upgraded to other 'bonus' units without the player being able to purchase any. I'm not sure if this will work, maybe there is another way but I can't think of anything else right now.

[GaryChildress]

Many thanks, ThvN!