<< This just a one detail of big model so it stay on it's position

Sure but you can open an another session in the same time and make Ctrl +C / Ctrl + V between the 2 sessions!
So you have your entiere modele in one, the "extract little object" in the another one where you have centered it on the grid!
Not a big deal to reput on the good position when you come back on the big object! One click on a specific snap point! :)
More easy working ;)