Car seat for tall 4 yo

[Birdie]

@fivedogs and other car seat experts, I have a question. I'm looking for a car seat to suggest to my mom to buy whenever BRU does their next trade in event. She currently has an old convertible seat that is about to expire that she uses for my 4 yo niece. My niece doesn't live in the same town as us, so my mom rarely drives her. However, whenever my mom is visiting or niece is visiting here, she always wants to ride with my mom.

I'd like to find a nice seat that my mom (or I) can install when she'll be visiting my niece. It needs to be budget friendly since she won't be using it that often. Niece is a tall 4yo who FF.

Any suggestions? Need more info? I'm not sure on her weight, but she's tall and skinny.

[Birdie]

Thank you! The sureride would also work for DS. I wasn't sure when the transition from convertible to HBB happened. Since it will get infrequent use with my niece we could have it threaded and possibly even installed (she currently doesn't have anything installed) RF for DS and then just flip and retread it for when she'll see my niece. She doesn't transport DS enough to have bought a seat yet so my plan had been to just install my seat in her car whenever we knew she would have him.

[Birdie]

Thanks!