Car seat conundrum

[Popgoestheronweasley]

I'm after some advice on car seats as I'm going round in circles trying to work out what is best.

We have a car with 3 full size seats in the back but isofix on the outer seats only (not on the middle seat) and no isofix in the front seat.

We have

• ds who has just turned 3 and forward faces in a britax advansafix (uses one isofix point) but he is 106cm and 19kg and while he is well within the 25kg weight limit for using the 5 point harness on the advansafix, due to his height we are struggling to do it up as the straps have to fit between his shoulders and the headrest and he's almost too tall to do this.
  
• dd who is 16 months and rear faces in a maxi cosi 2 way pearl, using the other isofix point and we would like her to remain in this seat for as long as possible
  
• dc3 on the way and no infant seat as he/she is an unexpected addition and we got rid of all baby kit after dd
  

So our conundrum is how we best seat all 3 children, the options I can see are

• keep ds in advansafix (although he will have to use it with seat belt very soon which I'm not keen on), keep dd in pearl using isofix points and get a non isofix base and seat for dc3 which goes in front seat when it's just me and the kids and in the middle rear seat when dh is with us
  
• get a britax 2 way elite (which I understand has better back length) for ds who then can go in the rear middle seat without isofix, leave dd in the pearl and get an isofix base and seat for dc3 who can then go in the back with the others
  
• another solution which I haven't thought of
  

I'm so confused - I really want ds in a 5 point harness for longer but options seem so limited and 2 way elite seems to be the only one which fits the bill but it looks a lot less sturdy than the advansafix.

Any advice appreciated

TIA

[AliceMum09]

Your DS has only just been 3, therefore it's not going to be safe at all for him to be using the Advansafix in high backed booster mode (regardless of the fact that legally he is heavy enough to use it this way), this explains why.

He'd be safer rear facing, I would buy the Two Way Elite (very good investment since you will have two younger children who will benefit from it too) and use it in the middle rear facing for him. Only thing is it needs to brace on both front seats so they'd have to be fixed in the same position as each other and you'd not be able to alter the driver's seat between you and your husband. I'd definitely try it rear facing though rather than dismiss it straight away because of these restrictions. But it would work in the middle forward facing. Then at some point you move DS to a high backed booster, DD to the Two Way Elite and DC3 to the 2Way Pearl.

I'm not sure I'd bother with the expense of a base for a new infant carrier, it's really not that time-consuming to belt one in once you've done it a few times and there isn't any safety advantage to a base. Sometimes having a base can tilt an infant carrier too upright for a newborn anyway, installing the seat without a base gives you a bit of room to adjust the angle of the seat a little.