[issue resolved] I confused the issue by using the word hotseat. in the FAQs it says, "If a Premium member is playing at a table, all restrictions based on location are removed for all other participants at this table." that suggests that in my example above, all players should have been able to play but that was not the case. The two couples who had a premium player in their house were able to play but the two players who were in one house separate from the house in which the premium member lived could not both play.
In my example, two of the players living in a different house/ip address from the premium members were using different computers but the same ip address (but different from the premium member). One of those two could not play and the stated reason was that two players could not play from the same ip address unless one of them had a premium membership. The person hosting the game had a premium membership but not either of the two living in the house with the player who couldn't play.
If one premium member hosting a game should be sufficient for multiple couples playing in different houses to all play, then I don't know what steps to take to make that happen. If we need one premium member for each ip address that has multiple players, then my original suggestion still holds. It would be nice to have a party premium membership, which could cost more, but would allow multiple players at multiple ip addresses to play as long as the host was a premium (party) member.
As another example, I am hosting a new years event in which I have invited 4 couples (each set of couples living in a separate house from each other couple) and I will have a premium membership. I can and will buy each of the 4 couples a single month membership to make this happen. However none of them are very tech savvy and it will be a bit difficult to get the to enter the gift code in the right spot. That's why a single one day use for multiple ip addresses would be so useful, especially during the pandemic when each set of couples must stay in the the same house/ip address
Answer: I had it all wrong. Depending on the browser, one player in the house must have set up an "remember me" option so that they wouldn't need to sign in again. When both players accessed the boardgamearena.com site from separate computers, they didn't make sure it was their login in the top right. Thus, while they both had separate accounts and separate computers, they were both trying to play from the same account (because the same player was automatically logged in on both computers)
