Adding an app

Unfortunately, the MFP staff doesn't read all the posts here, so you're just talking to other MFP users who have no more power to effect change than you have yourself.

Suggestions go here:

https://community.myfitnesspal.com/en/categories/feature-suggestions-and-ideas

I may be wrong, but in my understanding, MFP is open to new interfaces with sufficiently popular devices, but that this is a thing that would be initiated by the device/app manufacturer. The people who created the device need to program an interface that supplies certain data in certain formats to MFP. MFP makes information available to device/app companies about how to do that. You may want to lobby the company that provides MI Fitness to pursue this.