Adding 2 different "recharges at X"?

so I'm currently making this magic item that have 2 recharges

basically, one of them is "Recharge on Short Rest" and the other is "Recharge on Long Rest"

how do I add both?

You can’t. You really can’t do either one to be honest, the rest options don’t work. Please see the Homebrew Items & Equipment FAQ, question #4 for more information: (https://www.dndbeyond.com/forums/dungeons-dragons-discussion/homebrew-house-rules/131411-a-homebrewers-how-to-faq#HomebrewItems&EquipmentFAQ).

aw, that's a bummer, I suppose I have to go with the set of charge then

Sorry to be the one to deliver the news, but happy I could help by at least providing an answer.