When I try to add a new multi, using the Fiddler, the uoconvert.exe saves all items in multi as a static (obviously, the doors and sign-posts need to by dynamic to work). I know I can edit the multis.cfg file and set all the doors to dynamic , but it means that I have to create two versions of the multis.mul file (one, with the doors which I have to place in the multis.cfg file, and the other one for the client - without the doors).
I know that uoconvert can automatically detect doors and sign-posts in the houses attached with the client...
So, my question is: is it possible for uoconvert to detects doors and sign-posts in the houses created by myself?

uoconvert doesnt detect signs and doors it simply reads the flag value in the multi.mul entry.
Check with the MultiEditor plugin if signs and doors have the checkbox "Invisible" that will set the flag.
(Select the tile, expand (click) the bar under the toolbuttons)

Thanks for the answer! You're my Master! Works just perfectly.

No prob, btw the client needs the flag also, or you can never open the doors

Yep, thank you, Turley!
I had similar problem and now it solved!