Cat chasing other cat

My parents are having an extended home visit (for 3 weeks now) with one of my rescue groups' cats, a 4 yr old DSH spayed cat named Maddie. They currently have a 16 year old neutered male cat, Tigger. He has always been almost semi-feral as he was born on a farm and we got him when he was about 6-8 weeks old so he was not properly socialized as a kitten. He will run away from us and does not like to be held or petted for very long as a result. He has gotten a bit better as he has gotten older though.

My question is that Maddie has been chasing Tigger (I believe it is play and will observe it this weekend) and Tigger will hide or slink away whenever she is in the room with him. My parents are concerned that he will never get along with her and that he will always be afraid to come out and will always be hiding.

I have already suggested feliway so they have started using this. They have been keeping her in the basement while he is out and vice versa.

Any other ideas?

No, they probably won't, as they weren't properly "introduced." But it's only three weeks, which is just a spec of time in the big scheme of things, so I don't think you need do anything about it, other than keeping them separated when unsupervised like you're already doing.

In my experience, chasing with hiding probably isn't playing. At our house we have both. Chasing with playing, and they usually take turns. Chasing without playing is one always chasing another who usually then hides. (at my house anyway. I'm sure the feliway will help. )