Can i load step by step objects?

Hi to all, apprentice on TGEA 1.7

If this is possible...
what is the propose way to load DTS or DIF files in a mission step by step?

Is possible to load a building in real time into a mission? Can i do this with code?

etc. i have write a simble code for time control > date control > month control > session control,
with this controm i have make periods for Rain, day/night with changes in sun colors and replace of the sky.
I have delete the sky in the mission and working only with script code under the Newsky function.

Can i do this with the interiors of a city ? Loading thems with foot of cordinates?
what is the way? Is the way of automatic zones?

Thank you for the time