DD armbinder and converting CBBE to 3BBB

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I've been playing around with DD items to use on the 3BBB body.  The armbinder behavior has me confused.

The simple I'm not a pro at this steps I use with outfit studio are:

1) load the project..for example Kimy_Dress_Eb.

2) add project "SE 3BBB Amazing.osp"

3) select 3BBB as reference body

4) delete CBBE body reference(if it exists)

5) in bones delete L/R Breast(if they exist), 3BBB body has its own 1,2,3 L/R breasts

6) expand/shrink mesh to fix any problems

7) select all outfit meshes and copy bone weights

? conform all

9) save project

 

This has worked fine with some of the outfits and nipple piercings, they got that 3BBB jiggle,  but when tried on a armbinder it messes up the mesh in game.  The bottom ring on the armbinder gets warped, hands are missing(arm partially sticks out of the armbinder) and the straps partially sink into the skin.  Yes I have Zaz and use FNIS and the build order I use has been solid for years.

The Odd thing is if i do nothing to the armbinder with outfit studio and just build all with morph like usual, the armbinder works and looks fine in game.  Again, the CBBE armbinder works fine on the 3BBB body...How?

 

Are the DD CBBE armbinders a special case that don't use a CBBE reference body since they also uses Zaz?

What other kind of DD items would fall into this category of don't touch they work fine?