Import from gallery 2 - lost images order

I've a gallery2 with about 1500 images, ordered with orderWeight manually.
Albums are nested with 3-4 levels, like that:

->
-L->
-L->
-L-L->
-L-L>
->
-L->

I've no photos on level root, and level 2, but they are in level 3 and 4.

Importing albums and photos into gallery3 was successully, but I've lost my custom ordering. Is it possible to restore the order?
If i can map old items ids with new items ids, I can copy my OrderWeight to gallery3 weight column, but ids are different.

Is there any way to restore my order? It's extremely important.

Thanks in advance, best regards.