I don't know what to do. These birds are sleeping all day long sitting on the blinds rod. No fun at all. They totally ignore places where food is (like they are scared of this familiar places)

They are absolutely no fun. I m so tired of it.

I wasn't going to post in places in craigslist. Only in FB groups consisting of bird enthusiasts
But sure there is something to think about

question from body language
What does it mean when a bird makes frequent beak movement that looks like opening and closing beak with small amplitude (human analog is lips smacking) ? Trillie does it a lot. I honestly think he is trying to calm himself down, just like infants in orphanage rock to calm themselves down as there is nobody else to rock them (not sure if such a thing exists in this country but I read about it, in general)

PS it hurts to be a "cockatiel" now. I would rather still be a "lovebird"

It sounds like beak grinding, which is something that cockatiels do when they're feeling relaxed.

Some further development of the situation.
Slowly but very (stupidly) determinate, Trillie, the father, is getting Stella (his daughter) on his side. She still hangs out with Tator Tot (her sibling), but I also often see her sitting with Trillie like lovebirds. I don't see any mating... but I am guessing it may be coming soon. Trillie is courting Stella and when she is not answering he sings very annoying monotonous song. Its so annoying that I have to slightly poke him to make him stop.
Another daughter, Babyface, tries to attract Trillie's attention but he doesn't want her. Usually I see 4 of them together (Trillie Stella TatorTot and BabyFace)
One cinnamon is growing her tail back. Another is also trying to get Trillie's attention but no result.
The only more or less happy couple are Bella and Sparkle (siblings from different clutches). These two have been together for a long time and never had any conflicts.
The situation is going nowhere.
I still need to rehome probably all of them. My life is crazy busy and I don't enjoy it at the moment. Daughter is in cross country team, she needs to be at school every day at 6am in the morning. I am expecting background check results to start working, and my guess is that work is going make everything even much more complicated.

The risk of mating and trying to make babies will be highest in the spring. It's possible for cockatiels to breed at any time if the conditions are right, but they are more motivated to do it in the spring.

Sure.
The problem with rehoming is that I can't let them go randomly, like "here are 8 birds in my house, come get whoever you like". I would like their current bonds to be considered... If some birds are friends for duration of their lives, it would break my heart to have them separated. I would never let somebody buy a single bird from me if they don't own another cockatiel already.
How would you approach this issue, Carolyn? Would you just let people buy who they like?

It's a difficult problem, and part of the problem is that a lot of the bonds are incest romances. Another person might not prevent them from making babies together. Since your birds are used to being in a flock, it would be good if you can find homes where there will be at least one other cockatiel to keep them company. And letting two same-sex birds go to the same home would be a good thing if you can arrange it. But I'm not a big fan of keeping incest pairs together, it kind of seems like it's better to give them a chance to find a mate that's not related to them.

"he sings very annoying monotonous song"

Ah, the cockatiel mating call. Silver does that in Emma's ear, and has been for at least a year. It never amounts to any mating, though.

no I don't think this is the mating call. The mating call should be inspiring. I have a feeling that Trillie makes this song when TatorTot gets in the way, it's a very angry song, first of all. I need to make a video of it sometimes.
He never did it when Cuddles was around. This is the song full of frustration and even anger IMO