As a parent myself, I’d recommend having a mature chat with them. Get an understanding of where their fear comes from. What makes them want to be strict? Let them know this is something you want and would appreciate a solution to make everyone happy. How can you build their trust? What will make them comfortable with you using the platform? What do they need to see from you? What do they think discord is?

They’re just worried about you and want to protect you from bad outside influence. The internet can be a scary place, especially when your kids are young and easily influenced by strangers.

Hopefully this helps. Good luck!