if you only saved the breast moving as ds timeline, I think,, you can not mix it with another timeline for other V4 animation,
walking, or jump and down etc,, ds timeline can not be cut and copy, or save the timeline as new layer, I think.
But,,if you have animate 2, you can change your breast movement timeline as aniblock, and apply it as subtrack to other animation.
you can choose whitch parameter need or not, so even if you make the aniblock with mix parameter,(FBM or other rig rotaiton,,etc)
you can remove other parameter and keep it as only breast movement aniblock.
or if you record each breast movements as pupettier layer, (I think,, you can translate each keyframe status to pupettier dot, I think
and save it as pupettier layer duf file.but I did not try it with V4, I use only genesis,, .)
then apply the each dot poze with other timeline keyframe, as you like.
it seems easy , first make pupettier layer for V4 breast move animation, and save it as pupettier layer.
then open the scene, which recorded other timeline , load the pupettier layer.
first select the key in ds 4.5 timeline, where you want to apply breast movements
then in pupettier layer, with preview mode, click dot which you like.
it auto record the current status and apply the breast move on the key frame,
when you want to correct it, just click another dot, then record the current key frame.
first select the key of timeline, then click or choose dot of pupettier layer, in preview mode .
as for me,, this way can work.,,,
but I recommend,, you get animate 2 ^^; if you hope to make animation by ds 4.5 .
I hope other professional user may help you and advice ,,