Singapore Citizen and PR Buying BTO Together?

[kiwiinsg]

Hi, I have a question about Singapore PRs owning an HDB in this situation:

A Singapore Citizen (the mother) and a Singapore PR (the citizen's daughter) sign up to get a BTO together. The Citizen (the mother) is the primary applicant.

If later, years down the line, after they have had the BTO for a few years, if the Singapore PR's PR-status gets revoked because she has been living overseas for a few years and her re-entry permit renewal is rejected, do the mother and daughter have to sell the BTO?

Or can the mother (citizen) continue to own the house on her own?