I want to share my sadness. Maybe I'll get some help. I understand that for game is important only those characters who actively participate in the life of the town. Who cares about NPS-service? These characters occasionally appear in parks and occasionally perform their role when they are needed. But I care about every resident of my town, even if they live "behind the scenes". Today I suddenly discovered that two sims-NPS disappeared without a trace Their growing was not expected, so it can't be an explanation. Why they disappeared? And where can I find them now?

NPC Service Sims are not town residents, it's the same with homeless co-workers if your game generates those. They are best thought of as commuters in from another town. They are volatile and cannot be expected to remain stable parts of an ongoing game even if they do not age up out of service or if it seems like they do tend to stay in their assigned slots for a very long time. I do not believe there is any way to change that.

Okay, I made a mistake in the wording. But it doesn't change the point. A hundred years these characters were on the list and suddenly they disappeared. I already found out the Register was the reason. There, by default, the number of sims performing a specific role is less than the standard. However, there was no warning about this. I think I should find these poor sims in one of the recent backups. I hope they're still alive somewhere.

I don't know if this has changed over the years, but Register's default service pool sizes are supposed to be the same as EA standard.

It was probably meant to be, but something went wrong. Or I have things that don't happen to normal people. I started a new game to check what would happen. The victims were a social worker and an adoption agency. In each of these roles should be on two sims. Another strange thing is that one of the roles lost its Russified version after installing the mod.

As I recall, that is correct on the default service pool size being/supposed to be 2 for each of those two positions. Chain will want to know this if he is able to assist, but which exact version of Register are you using again?

I'll be happy if I can continue to use Register in the future. I use the version for my game - 1.57. I assumed the newer version has new options, but I thought the default settings would be the same. Could you also take a look at the screenshots? It's just a confirmation of strange things. The filter was called in both cases with using MC.
https://yadi.sk/d/pTkW1q3Q7dU1uA

The default size for those services is 1. Check the homeless pool and see if they got sent there I remember one time when I forgot to install Register and had 2 Child Abuse Social Workers Carlos Santos and Linda Duran both pre-made service sims in Sunset Valley after I had installed Register Carlos ended up in the homeless pool stripped of his service status I can only assume he wasn't annihilated because he was pre-made.
Game generated service sims such as when I was test playing a custom world and put Register in after I decided to play a game there those that exceeded the pool size got annihilated.

sittingbear, I checked the entire population. They are neither among the dead nor among the living. In towns there were always two Sims in the role of social worker and an adoption agency. After the register was installed, the pool value changed, but this should not have happened.

I checked in the games Gameplaydata for those 2 services by game default should only have 1. The game has a habit of forgetting that it already assigned a sim(s) to a service and assigns another to the same service exceeding the pool size. Register enforces the pool size so yes it should happen.