Shireneko
Well, I don't know if you thought of this, but you could add them being on the other side of Loki family recruitment day, and have them help out, especially since the 2 Amozon girls are there, maybe even Bete, if he join during this timeframe? Then have them help train new recruits, along with Finn and Elf and Dawrf, have them help more against Evulis group, etc. Also, if you haven't done this already, then I suggest creating a notebook in IRl, or something on your computer or phone, the list every Magic Card idea used in the fic so far, along with the abilities that affect Aiden Magic Card, in one section. Then every Magic Card idea you created, but haven't used in the fic yet, in a different section, then for the 3rd section, you can create a new page or chapter in this fic, and have us, your readers, suggest or create new Magic Card ideas, in which you can consider at your own leisure. And if you do accept the said card of choice, give a shout-out the person who came up with it, something like this would no doubt turn into a competition, on who will be given a shout-out during this opportunity during the story, and who will be next. Hopefully, this will help you, and make it fun for you and your readers. With that being said, I suggest reading if you haven't already: "Playing with the supernatural" on Webnovel, Kisuke and Yoruichi from Bleach are the Main Characters, in Highschool DXD, and them some how crossing over to Danmachi. And there are a lot of good ideas, and new take on how the Danmachi System works, maybe you might consider asking the Author, if you can use some of their ideas, or something, or maybe even come up with your own.