Baldur’s gate: hire someone as “mercenary”

In Baldur’s Gate 1 and 2 (underlying dnd 2e, forgotten realms), you can add certain members to your party, and remove them freely. When you remove them, they keep the items they wear (which you can strip the moment before), and take no gold with them. I’m trying to roleplay a little, and this is absurd. So, what would be a fair amount of gold to give to a party member for being in a party for some time?

Some thoughts/additional points:

  • I read somewhere that this might be relevant to the amount of battles done. Let it be known that in this case, the amount of battles is maximum: everyday has many dangerous battles.

  • Splitting the party gold is one idea. It still might be unfair if the other characters have used gold to buy more expensive items than the npc leaving.

  • A specific amount of gold per days spent in party would be another idea. I’ve read that this would be dependent on level?

I am hoping that there would actually be some rule about this that I am not aware of.