For better internet search via Google, I would suggest using
this title >

Polish Blue Nativity Manger Lot Scene

…Hope this might help and good luck!

Without photos’ it’s pretty hard to help.

Is it ceramic?
Porcelain?
Handmade or a commercially made set?
What sizes are the pieces?
Are the pieces shiny glazed, matte finished, or mother of pearl finished?

There were a lot of nativity sets made in ceramic shops around the country by individuals for their own use, so it could be one of those sets.

There were also many commercially produced sets, but I would think they would be marked,
or at least some of the pieces would be.

This isn’t really an answer, but I have a similar set, not for sale, though. Mine is a HANDmade set, and thus it does NOT have marks on the bottom, not even initials that porcelain or potters or ceramic artists might apply to ’’greenware’’ ~ if you’re selling it, maybe list it as OOAK or One of a Kind, or RARE, or at least list it as UNIQUE and UNUSUAL, but don’t use CAPS in your title, or Google will not show your listing!
It’s probably porcelain, and/or a highly glazed ceramic set…it sounds to me it probably IS hand-painted by a ceramist. Queenmum’s inquiries are excellent, follow her lead, too, I Encourage you!
If you need help adding a photo here…copy and paste the link (it will start with http and end with probably a jpg extension) Put an exclamation point BEFORE the http no spaces, and put an exclamation point right after the jpg or extension, do NOT use any quotation marks if there are any before the http and/or after the jpg., and a pic will show up here for others to possibly help you out! LuckBlessings Be to You in researching your Nativity! :)

My mother made a set when she did ceramics and used mother of pearl blue glaze. It is a beautiful color.