@Geejay1945 The general answer to that would be NO, one device on checked and leave you to sort out everything else, Installation has time restraint's on it.
Is it an Openreach organised FF Full Fibre upgrade, the Engineer is there to get your Fibre up, check it's working and if he assist's you then that is well beyond his call off duty, see the video as linked below for you. If you need help in doing the connections, EE does offer a paid service or it may be free depending on what you have from them.
If you say what you have EE/BT Hub wise currently that will help, new EE Hub sent then it sounds like it will possibly be required if there is a Landline Phone involved and you are going DV Digital Voice operation for the phone.
Bing Videos
What to expect during your Full Fibre installation | Openreach
