The shield could have also been woven by a circle, and held by Moiraine, using her angreal. Rand could break free when 3-4 Sisters, all weaker than Moiraine, were holding his shield, after he broke the knots of the other sisters who had abandoned the shield for the battle against the Shaido. Moiraine has a significant angreal, however. Her ability to hold a shield woven by a circle might match or exceed that of 3 sisters who were somewhat weaker than her.
Also, shielding Talents are a thing. No single sister has Breowyn's ability, but it's a gradation. Moiraine could be better at it than the average sister.
Yes, I'm hoping there a bigger circle off screen. Still, I'd be surprised if they honor the series 100% - I wouldn't be surprised if they let Moiraine hold Logain alone because she and Siuan are 'strong' and everyone else needs to link. They might simplify things for people who haven't read the series.
Fan of Lanfear