How to wire 2 "smart" doorbells to the same chime?

[itm]

I have a Siemens Gigaset HC450 door intercom, installed with a Friedland D107 chime. The Siemens Control Unit is powered by a 12VAC 1A transformer, and the chime by an 8V 1A transformer.
I also have an Ezviz Smart Video Doorbell, powered by a 12VAC 1A transformer. I was wondering if it would be possible to connect this video doorbell to the same chime as the Siemens system, as the Friedland chime has 2 spare terminals - the Siemens system is connected to the 0(F) and 3(T) terminals, but the 1 & 2 terminals are unused.
These are the wiring diagrams for the two doorbells:

ezvizdb1c.jpg (63.8 KiB) Viewed 953 times

...and here is the same for the Friedland D107 chime which I'd like to connect the 2nd doorbell to:

honeywell.jpg (50.53 KiB) Viewed 953 times

(TBH I don't understand the difference between the two wiring examples in the Friedland D107 diagram).

Could anyone advise:
1. (How) can I connect the Ezviz video doorbell and transformer to the existing Siemens/Friedland setup
2. Should I retain separate 12VAC 1A transformers for the Siemens and Ezviz doorbells, or would it be feasible to power them both from the same transformer?

[Someone-Else]

The "power kit" would need checking for compatibility to avoid anything going bang or at least "poof" *

Are you also aware that once the video doorbell is wired, like most "smart doorbells" it takes just over 7 seconds to notify you something has happened, and so you then have to remember which pocket your phone is in, grab it to accept the notification to see the back of a delivery person as you took too long to answer.

* Your friedland doorbell can only go ding-dong or just dong. The problem is that if the 2nd doorbell button just goes dong you will naturally assume you only heard the dong and missed the ding and in so doing answer the wrong device (Seen it done countless times)

Your choice, but I wouldn't waste £100+ on something that is nothing more than a gimmick

[itm1960]

Haha yes I hadn't considered the (literally) ding-dong battle between the two doorbells. I plan to work around that by using a Zigbee sensor on the doorbell to trigger other audio alerts around media players in the home (we often don't hear the doorbell anyway), but that's another story...

The video doorbell is brilliant actually. It rings the existing wireless chime in < 2 seconds (but it's not very loud), and it's <5 seconds between the doorbell press and getting the alert on the phone. If I can't be bothered to get the phone out of my pocket I can still hear it anyway, which is better than the doorbell chime as I'd hear it even if I was at the bottom of the garden. Or next door. Or down at the corner shop. Or.....

It would just save a bit of drilling and cabling if I could use the same chime for both doorbells.

The power kit is only required if you want to connect to a physical chime. I assume that it varies the current across the connected terminals so that the chime can be triggered

[Someone-Else]

I assume that it varies the current across the connected terminals so that the chime can be triggered

Here in lies the problem, we don't know exactly what it does do.