Hello vb2509,
Just an heads up, I’m not a lawyer so take everything I say with a grain of salt.
According to the Marketplace Distribution Agreement which you can find here: Marketplace Distribution Agreement - Unreal Engine , and the high-level overview https://www.unrealengine.com/en-US/marketplace-faq . I’d say yes this will violate the above mentioned agreement, as these are not your animations (even if modified), you cannot redistribute them onto the marketplace, any other marketplace or sell them otherwise (as in reselling them as a part of an asset pack. I do not mean a finished product - game or software). I’d also like to point you towards this article Marketplace Guidelines - Unreal Engine on the subject matter (Point 2 especially). There’s also an complete forum dedicated to the marketplace itself.
So in short, you’re not allowed to redistribute assets from the marketplace, in that regard.
Hope that helps.
Regards,
Vecherka.