Have either you or your sister talked to her doctor ? Her doctor should be able to recommend local support groups who can help her cope. For now, you both might want to check out these websites. www.lymphnet.org/patients/supportGroups.ht
If you search on lymphadema, you might be able to find a support group in your area that you can contact.
Talk with her doctor. Her doctor should have resources for her she can use while she prepares for her surgery.