When merging calls on iOS, after connecting the second call keep user on RC screen where merge option exists. This is also Accessibility issue, see comments at bottom.

Today upon connecting first call, user stays in RC App (see 1CallCnnctStaysOnRCScrn.PNG) and can click + to add new caller. User only goes to iOS Lock Screen after inactive screen time and that screen has RC button to return to RC app (see 1CalliOSLockScrn.PNG). The RC button is great reminder that user is not on RC screen.

When adding a second call, upon connecting, user is immediately dropped into iOS native phone "lock" screen (see 2CalliOSLockScrn_NoRCButtonMergeDisabled.PNG) where disabled merge button is presented in same position that, when on a single call, a return to RC button exists. Without the RC button user may believe they are still in RC App (like when they do a single call).

User has to swipe out of the native iOS screen and select RC screen to return to the RC App to merge the calls (see 2CallCnncAftrRetrnToRCScrn.PNG). This is a pain and keeping user on RC screen after connecting second line would allow user to merge calls (the most likely objective when initiating an added call). As alternative, convince Apple to keep RC button on the Lock Screen when multiple calls are active.

Also, this would be very confusing to users with limited sight because: 1) they are immediately taken to a screen not related to the app they just dialed a second call from (unexpected behavior); 2) they lost the return to RC button they normally see when a single call is connected to the device (overloading button location); 3) difficulty seeing small grey merge arrows on the disabled merge call button (low contrast icon); and 4) the merge call button is disabled on Lock Screen but can be performed if they can find their way back to the RC screen where they just finished connecting the new call (over complicated user experience).