Upgrade of ships?

[peterw]

In the next version of my mod (Italia Victor!) will be buyable ships (core units).

I've alreads implemented to buy ships, but they can't be updated to better models.
I can't find something relevant in the code.
The flag "noupgrade" is not used for the relevant ships.

Is this hard coded and therefore no solution at all

Thanks
Peter

[Razz1]

They need to be in the same series.