thanks for the help, they both have britax car seats, the youngest is still rear-facing Advocate, almost 2 y.o. and about to be front facing, the 4 year old is front-facing Frontier - both are the click n tights and newer.
Good news and bad news. The Frontier is compatible with the inflatable seat belt system but the Advocate ClickTight is not. The Advocate can use the vehicle's LATCH lower anchors until the child weighs 30 lb in rear-facing mode, 35 lb in forward-facing mode. Depending on how much the 2yo weighs, if you could possibly make it another year to year and half before he/she hits 35 lb, you could pass down the Frontier from the older child then, and consider a dedicated booster for the older child at that point when they are close to 6.
If you want to make life easy, I'd suggest snagging a second Frontier now while you can still find one. They were discontinued last year so stock is dwindling down. Britax's replacement for the Frontier (the Grow With You ClickTight) is NOT compatible with the inflatable belts. Albee Baby is one of the few reputable retailers I know of that still has some Frontiers in-stock:
https://www.albeebaby.com/britax-fr...xAgY6tNh4OeitGq3u44fuufLyjyzX_1hoCu-kQAvD_BwE
You could also consider any of the Graco combination seats like the Nautilus, Atlas, or Tranzitions/Wayz which are all compatible with the inflatable belts. They aren't quite as "nice" as the Britax seats.
If you have a 2nd row bench, you could put the Advocate in the middle with the regular seat belt or in the center of the 3rd row where the head restraint is removable. The outboard 3rd row seats have compatibility issues with most forward-facing seats due to the non-removable head restraints.
o Installation with a Ford or Lincoln inflatable seat belt system:
▪ Refer to the CRS User Guide for installation Lap-Shoulder Belt.
• Frontier 90/CLICKTIGHT and
Pinnacle 90/CLICKTIGHT the lap-shoulder belt is routed through belt path with CLICKTIGHT open
▪ While holding the shoulder and lap belt portions together, route the vehicle belt through the appropriate belt path. Be sure the belt webbing is not twisted.
▪ Continue installation as per the Ford or Lincoln Vehicle Owner’s Manual:
• Insert the belt tongue into the proper buckle (the buckle closest to the direction
the tongue is coming from) for that seating position until you hear a snap and
feel the latch engage. Make sure the tongue is latched securely by pulling on it.
• To put the retractor in the automatic locking mode, grasp the lap portion of the
inflatable safety belt and pull upward until all of the belt is pulled out.
• Allow the belt to retract to remove the slack (storing excess webbing).The
retractor will click as it retracts to indicate it is in the automatic locking mode.
▪ Continue installation as per the child restraint user guide – closing CLICKTIGHT.
▪ Verify that the vehicle belt is tight and that the child seat is secure. The child seat is
secure when it moves less than 1 inch (2.5 cm) front-to back or side-to-side at the
vehicle belt path.
▪ Attach the Versa-Tether to a designated anchor (see vehicle owner’s manual) and
remove slack.
• NOTE: Top tether use is always recommended by BRITAX.
The Frontier's install with the inflatable belts is only slightly different than it is with a standard belt. You just have to add the step of switching the lap portion of the belt into automatic locking mode by pulling it all the way out from the lower retractor before closing the ClickTight panel.
o Installation with a Ford or Lincoln inflatable seat belt system:
▪ Refer to the CRS User Guide for installation Lap-Shoulder Belt.
• Frontier 90/CLICKTIGHT and
Pinnacle 90/CLICKTIGHT the lap-shoulder belt is routed through belt path with CLICKTIGHT open
▪ While holding the shoulder and lap belt portions together, route the vehicle belt through the appropriate belt path. Be sure the belt webbing is not twisted.
▪ Continue installation as per the Ford or Lincoln Vehicle Owner’s Manual:
• Insert the belt tongue into the proper buckle (the buckle closest to the direction
the tongue is coming from) for that seating position until you hear a snap and
feel the latch engage. Make sure the tongue is latched securely by pulling on it.
• To put the retractor in the automatic locking mode, grasp the lap portion of the
inflatable safety belt and pull upward until all of the belt is pulled out.
• Allow the belt to retract to remove the slack (storing excess webbing).The
retractor will click as it retracts to indicate it is in the automatic locking mode.
▪ Continue installation as per the child restraint user guide – closing CLICKTIGHT.
▪ Verify that the vehicle belt is tight and that the child seat is secure. The child seat is
secure when it moves less than 1 inch (2.5 cm) front-to back or side-to-side at the
vehicle belt path.
▪ Attach the Versa-Tether to a designated anchor (see vehicle owner’s manual) and
remove slack.
• NOTE: Top tether use is always recommended by BRITAX.