Well this has got me thinking as I too have the passener airbad turned off most of the time, so dare I suggest it, I decided to RTFM
I have two boys, 4 and 2 years old. Both love to ride in the front in a forward facing seat in both my Q7 and RS4, according to Recaro front seat is fine for this seat
https://www.recaro-kids.uk/monza-nova-is.html
The Q7 manual states in the "deactivating passenger airbag" section, "If you have no alternative but to install a rear facing child seat on the front passenger seat you must deactivate the airbag" - "Turn it back on ASAP"....
As Volvo has been mentioned also, I took a look on their website for the XC90 manual, which again shows only to disable for rear facing only.....
https://www.volvocars.com/uk/support...ar-s-seatbelts
I keep the seat positioned rearward already, so maybe, I should turn it back on and then when SWMBO gets to ride up front it is one less thing to remember.... maybe
"Too small" is probaby covered here now,
https://www.gov.uk/child-car-seats-the-rules, "Children must normally use a child car seat until they’re 12 years old or 135 centimetres tall, whichever comes first".