Yes. Select Add Fund, choose the 529 fund type, and add your 529 plan name, state and Ugift code if you have one. Under Contribution Methods, pick Ugift only if you want guests to be able to give right now: they give through Ugift, not through in9months.
Online card contributions aren't open yet. A 529 fund that also allows cash by card shows as Opening soon to guests until they open.
Still stuck? Email support@in9months.com and we'll reply within 1 to 2 business days, or browse all help articles.