You should be able to keep the AzureAD B2B connection as a button in the New Universal Login widget. For the rest of SAML connections you can utilize Home REALM discovery while for the non-federated users - use a regular database connection.
For these settings, I suggest using the Identifier first login experience so that a user is first presented with a screen to enter their email.
Thanks for quick feedback, i already explore it and seems you suggest is very helpful for us to decide what we need to do
last question if i may or do i need create another topic for this
Is there any limit for number of domains assigned to a single connection and number of connections created ?
There is a limit of 1000 domains per single connection and up to 10 connections per Auth0 tenant for free subscriptions or up to 100 connections per tenant for paid subscriptions.
If you would like to read more about quotas, I have left a link to our doc.