I know theres something in HL2's hammer, but in HL1's hammer not sure. There should be a relationship entity where you can define relationships to player and other npcs. d_ht 99 d_li 99 that kinda thing. For example, you can make an allied Combine Soldier in HL2.
I've never mapped for GoldSrc so I don't know if that is in Hl1.
And theres also squad flags, I know for sure they are there.