Grappler Feat / Moving Two Grappled Creatures

Hello, all. First time poster here and relatively new / inexperienced player. (Member on Beyond for years, but have only played about 15 sessions all time.) Apologies if this is asked and answered elsewhere, but I couldn't find quite what I was looking for.

Obviously the Fast Wrestler portion of the Grappler Feat does what it clearly states, but I'm wondering if there is an official clarification or general consensus on how moving *two* grappled creatures your size or smaller should be ruled (ie, whether moving two creatures *would* then cost extra movement). Additionally, if anyone would be so kind as to point to any rules wordage that helps support whatever position yours may be, that would be greatly appreciated (by both me and probably my DM, lol). 

Naturally, as I am the grappling Monk here, you can probably guess which answer I'm hoping for. Lolol. But funnily enough, what makes the question pressing in the immediacy is not for offense, but for defense, as when we pick up our next session, I'm up in initiative order in a combat I'm afraid we can't handle (the party is split, because of course it is), and am hoping to grapple the two party members present and GTHeckO. (If they don't object, of course.)

In any case, nice to meet you guys and thank you so much in advance.