Combi Coccoro driving me CRAZY

[StoriesInTheSoil]

I LOVE my daughter's Coccoro for the way she fits in it and the ease of use for harness use.  I HATE the way it installs.

I drive a VW Passat wagon (2007) and have two rearfacing children.  My son (2.5) is outboard (passenger) in a RFing Radian XTSL, installed with a seatbelt and top tether.  DD needs to be in the middle which does not have LATCH so it must be installed with the belt.  I have tried a lot of tricks to get the Coccoro installed well including over-reclining it so that I have a lot of leeway for pushing and tightening it to a rock-solid 45* angle. 

I DO have the foam block that they send when you call Combi and tell them the Coccoro won't install.  It doesn't fit well between the seat-belt buckles but even when wedged in there and used, it doesn't prevent the issue I'm having (really I have NO idea how that silly foam block is supposed to help anything at all.) 

The issue is that I get it installed super tight but then if the seat gets bumped at all (bound to happen) it completely un-installs itself!  

What should I do?

[MariesMama]

Is the seatbelt locked?

[StoriesInTheSoil]

Yes, the seatbelt is locked with the shoulder belt routed flat on the car's seat back (as opposed to around the back of the Coccoro)

[BathrobeGoddess]

can you cut the wedge on the side to make it fit well between the buckles? the wedge is to keep it from pushing forward (like it is cocooning) and coming loose. have you thought about using the belt around the back to help the problem? It is entirely possible it just isn't compatible with a. your car or b. the middle seat of your car.

[an_aurora]

Did you try the Euro belt routing?  Some people have better luck with the Euro routing and using the blue lockoff instead of locking the belt at the retractor. 

[StoriesInTheSoil]

This is how it was in originally but it still uninstalled itself with the smallest bump.  

I still don't understand what that little foam block thing might actually do.  When the seat cocoons it does it where the lip meets the car's seat back, right up and over the block. KWIM?
 

Originally Posted by an_aurora 

Did you try the Euro belt routing?  Some people have better luck with the Euro routing and using the blue lockoff instead of locking the belt at the retractor.