It is possible to circumvent the restriction of not allowing multiple records by adding records in the linked table.
For example, Table1 has a list of addresses. Table2 has a list of people, with a field Address that links to Table1. It is set to not allow multiple records (people generally only have one address!). However, a field called Table2 now automatically appears in Table1, which I think of as a reverse link. It is possible to create a new record in Table1 that links to a name that already has a link to Table1. Thus when you go back into Table2, that name now has multiple records in the Address field.
Of course, the “reverse link” field can be removed from Table1. But sometimes it’s useful! Given the total lack of cross-table querying in Airtable, I’m having to use multiple lookup and rollup fields in all my tables, and I generally need these reverse links to do that.
(Proper queries would be really nice!)