Would love advice! Split family of Semi Ferals - Re-capture or Leave outside?

Hi everyone! Thank you for reading my post.

I will try to not make it too long! Here is my situation...

Mama Kitty, had 1 kitty last April. That cat is still coming and going in our yard though not everyday and needs to be fixed/checked to see if its a girl with a litter.

Then Mama Kitty had 4 more in Sept/Oct. ALL girls. 2 all black, 2 all grey. Caught them at 5/6 months old and fixed all 4. Clipped ears. Made "cage" and shelter for them to keep safe so I could socialize them and home them.. 2 escaped 2 days later.  

This is where they were.. (and the two that escaped hide)

 
This is where they are now


Heartbroken and depressed, I failed to try and catch them again thinking they'd never trust me again and it was hopeless. But they came back!

I now have a grey and a back inside and a grey and black outside. 


The grey outside hardly comes around but the black one seems to have clung to the "big sister" (April kitty) and is so loving and excited when it comes around, follows it all over and bumps her.. Otherwise it seems she's is alone alot.

I feel so bad she is alone and might miss her sisters? I worry the ones I have inside miss the outside twins and vice versa and not sure if i should leave things be since they are all fixed and just try to catch the ones that are not fixed or try and capture the whole family again and reunite the 4 and let the big sister go after fixing ( but then i worry she will be alone then

I have an outside "forte" We built   so the cats can be inside or out (via a portal in our window)
and can hold 4 cats easy.

It is mean to catch them at this point and try to save them/socialize them??? ( I can do it, it just takes time) or is it like tough love and good?

I am taking them from birds and family and bugs and mice and putting them in big cages. (The two I have inside are 2/3rds socialized now and run around the bedroom too when I open inside cage, so sisters would be able to roam somewhat too but not further than the bedroom and forte)

I also wonder if this is cruel. keeping them in or is it kind? Im confused. I love animals SO much and I want to save all I can and socialize them and help them find a home. 

Please help. I know everyone asks that, but, i'd appreciate it!

Thank you.

You have a great set-up there!  I would continue working with the ones inside and see how they do.  In the meantime, I'd definitely trap the remaining cat and get her fixed.  Two reasons - no more kittens and it will help you make the decision whether she can be reunited with her siblings.

Can you expand your set-up to include her?  That way, they can each have outside access without the danger of running loose.

BTW - where's Mama Cat?  If she hasn't been spayed, put her on the list, too.   She will probably feel more comfortable outside but she should be spayed.

It isn't cruel to keep cats inside but some feral cats don't make the adjustment.  If they are provided with food and shelter, their lives are vastly improved, even if they choose to live outside.  I personally can't stand the worry about them when they roam, which is why I built an enclosure.

Blessings on you for helping them.