Azure AD makes sharing and collaboration seamless for any user with any account

We've encountered a few issues in the previous (non-OTP) B2B model. E.g. when the invited guest is from an email domain that corresponds to an actively owned/managed AAD tenant, but that organization has not created accounts for their employees in this tenant (and is probably not using o365 for email). In cases like this, invite redemption fails. OTP improves on this, in that if the account does not exist in the tenant, the invited guest gets the OTP experience. But we have also encountered users who do have an account in a actively owned/managed tenant, but don't know the password, and SSPR has not been enabled in that tenant. OTP would not help us in cases like this. To work around cases like this, we need to be able to force federated "External Azure AD" users to be treated as OTP guest users in out tenant. Without that, we'll still have cases where we are stuck - particularly if the IT group in that other org are uncooperative (happens all the time).