4. Skirt is ready but grouping in Poser is terrible, then I selected part of skirt, which should be constrained group in Wings.

Select horizontal edge 2-3 rows from top. Press "L", later shift + "L" and under RMG choose materials. If you click on .materials. with LMB you can choose existing materials, but with RMB you can create new. Name and attributes are not important - it is only selected for easier work in cloth room, later can be deleted. I named new material "constr".