Smartwatch Garett - how to marry a watch with a phone and a bluetooth headset?

I have a g5 garett G5 smartwatch, I would like to see incoming calls / sms on the watch and talk over a bluetooth headset, making a conversation so as not to pull the phone out of my pocket. It's impossible to do that, why?

The description of the watch and its functions are here: https://www.garett.com.pl/o,389,SmartWatch_Garett_G5_czerwony.html
In addition to the above mentioned watch, I have a bluetooth headset plantphone 10 and a smartphone z v987 on andorida 4.2.1 (root). The watch and the handset pair nicely with the phone, but
1) or I can listen, talk through the watch
2) or listen, talk via a bluetooth headset.
I am not able to separate the phone signal from the receiver and messages / notifications about the callers on the watch.

On the phone, I tried to select the Bluetooth profiles of a connected watch or a type 1 headset. Phone profiles 2. Multimedia sound and nothing helped. I do not have any applications installed on my smartphone. Technical department garett.eu is not able to help me, they said that it may be worth installing applications such as:
https://play.google.com/store/apps/details?id=com.mtk.btnotifications1&hl=pl
https://play.google.com/store/apps/details?id=com.mtk.btnotification&hl=pl

Have you had a problem to connect several Bluetooth devices to your phone?

Have you tried to pair a phone with a smart phone and then a smart phone instead of a telephone?

I have not tried it, and rather it should not come out, rather everything pairs to teleofnu, do you have any solution in mind?