We are returning next year for our 5th visit to CN we are Romance Rewards members and always look forward to the Repeaters Dinner.
Friends of ours will be there at the same time as us and, although they are repeaters (previous visit was in February 2010), they did not join the RR program at the time of their first visit and since more than a year has gone by, they cannot get credit for their first stay.

However, will they still be eligible for, and invited to, the Repeaters Dinner?

Is that for all repeaters, regardless of whether or not they are active members of RR?