Can you use LATCH and seatbelt at the same time?

[acmom]

I have been trying to install the Maestro into grandparent cars. I can't get it tight enough with either the LATCH (I can't find any tether) or the seatbelt alone - it slides around too much. However, my dad worked on it for a while and did get it tight using both the LATCH and the seatbelt. Is there any problem with doing it this way?

[jerigirl]

Nope. Can't use both. Are you installing FF or RF? What kind of car? Maybe someone can offer some suggestions.

[acmom]

FF in a Mercedes convertible.

[legaleagle]

I think convertibles are exempt from the top tether requirements. Have you successfully installed other seats in this car? How old is your DC?

[rin]

Nope. Can't use both. Are you installing FF or RF? What kind of car? Maybe someone can offer some suggestions.

Uh-oh, I'm confused now. I thought the recommendation for boosters was to have them installed with LATCH (so they don't become projectiles in case they're unoccupied during an accident), and then of course to use the seatbelt. Is that not true, or how does that differ from a convertible seat installation?

[legaleagle]

When you're LATCHing a booster, it's only holding the weight of the booster itself, not the weight of the child in the seat. The child is still being restrained by the seatbelt. You don't need to LATCH the booster to prevent it from becoming a projectile, you can just buckle the seatbelt over it.