// this registers my custom sheet in Options:

/*
optionPanels.pnl_myCustomSheet = { // pnl_myCustomSheet needs to be unique in order to not interfere with other addons !
    name: 'My custom sheet'  
};
*/

// and this is how to register it sub to 'General' :
optionPanels.pnl_General.subPanels.pnl_myCustomSheet = { // pnl_myCustomSheet needs to be unique in order to not interfere with other addons !
    name: 'My custom sheet',
    //order: 35
};