Iso fix Car Seats for a BMW

[Wallaroo]

We have decided not to purchase an MPV but to use our BMW when baby no 3 arrives.

We want to get 3 new isofix car seats (cheaper than a new car!!) so I will need a booster seat for my 5 year a forward facing seat for my 3 year old and an infant carrier. There are only 2 isofix point though so which seats should be isofix and which one seat belt only?

Any recommendations?

I would personally use a seatbelt for the baby carrier, as it is the one you will use for the shortest duration. I also find the toddler and booster seats with belts more difficult to fix into the car than the infant carrier. That said, I have not reviewed any information on which of the seats are the safest.
HTH

Oh, and I have a Britax 123 Isofix booster for DD1, which is really easy to fix into the car. Would recommend it.

We have chosen Maxi Cosi Iso fix seats because they come with very high safety ratings,
and we have found them to be very easy to take in and out of the car,
have also found them very easy to use with seatbelts in my dads car (which doesn't have the iso fix loops)
But aren't exactly the cheapest option.