DD too tall for group 1, too light for group 2

[Littlemisstax]

What seat(s) would you use for DD? She's 3.3, and the tops of her ears are almost at the top of her group 1 seats (Britax Duo Plus in DH's car and a Trifix in mine), but she's only 13kg.

We'll need seats for both cars, I have isofix, DH doesn't. Budget not really an issue (more concerned about safety after a rear end shut with DD in the car) but would like seats to last.

a 123 seat maybe? We had the Britax evolva 123 seat for ds - the harness does them until 18kgs and then they can be strapped in using the adult seatbelt. There are also similar seats that use an impact cushion instead of the harness.

Kiddy Guardian Pro is an example of a seat with an impact cushion

Yes, you need a Group 123 combination seat- you can use the harness right up to 18kgs (the same as your Group 1 seats) but they generally have adjustable headrests so will be able to accommodate your tall, light daughter.