Pls help with infant car seat and perhaps new stroller ?

We are expecting 2nd baby and we used graco snugride with DD as infant car seat, but we can't "re use" anymore for second time since it had been in car accident once. So, we plan to get a new infant car seat and base.

Our 2.5-year old DD (will be 3 by the time baby no 2 is here) is now in BJCM single, but honestly, we hardly used it lately because she hates to be in the stroller at this age, unless we go to a mall or zoo and she gets tired after walking and wants to sit or take a nap in there. So, DH suggests that we just buy the adaptor so we can install the infant car seat on the BJCM and eliminate the need of purchasing another stroller for the baby. My only concern is that what if DD needs the stroller off and on when she gets tired, etc ? I know they sell the glider thing for the BJCM , but that's only for standing. Anyone with this experience before ? Would you get another stroller or even get the double stroller ? Thanks in advance for your advice.