Here is a good tutorial on fixing breaks in clothes: http://www.evilinnocence.com/xd-pose-fix-tutorial/

While it's about fixing CrossDresser breaks in the clothing, it sounds like you're having the same issue so this will probably help. 

I've found that BVH files tend to work better on the Daz figures and really work well with Gen 4 figures. If you can afford, TrueBones has a very nice collection of more than 2500 he often puts on sale for $69. These have been edited quite a bit and with the Daz figures, there are no missing bone errors. Still not perfect, but they are the best BVH files I've found for using in Poser.

Strangely enough, I've also found that PoserPro (the pro version of 7 that is, not the latest) handles them better than Poser 7. It's possible it some other factor, but when I upgraded my system with my tax refund this year, I upgraded to Poser Pro as well and did a series of side by side tests on two different computers, two different versions of poser and two different OS. I didn't expect to see any significant difference in loading in BVH files, but there was. The same BVH imported to the same figure and the results were much better on my new i7 with Win 7 and Poser Pro than on my duo core with Poser 7 and Win Vista. Don't have any idea why really.

PhilC has a very good set of tools for editing BVH files in Poser. Give you things like symmetry, reversing, fixes spikes, smoothing and a few more tools I've not really played around with.

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