Seventh Sister

i would recommend checking out the Facebook group for Builders, A lot of them are 501st members and can help you find parts for putting yours together.
www.facebook.com/groups/2024857891089043

as for our member their armor is 3d printed

but i don't know about their Soft parts and where they got them from.
my guess is there isn't a lot of vendors for this costume so it should be straight forward answer when asking people.

Boots probably crowprops they supple alot of 501st boots, more expensive but they are custom fit and comfy for long troops, really helps the feet.

crowprops.bigcartel.com/product/seventh-sister-long-boots


soft parts
looks like they did the clothes for the 501st Model that made the CRL, so nothing more accurate then the one who made the CRL.

www.bbeautydesigns.com/product-page/seventh-sister-star-wars-rebels-uniform