P&T Sport double kit question

[EMS23]

We've just been given a Sport V2 for free, in anticipation of DC2 arriving early Sept. DD will be 22mths and is quite small.
We have both seats with what we've been given so I need to buy a few add on's but am not sure exactly what.

1. I want to put the newborn in a car seat at the same time as toddler is on the lower seat. Can I do this and what do I need to buy?

I guess car seat & relevant adaptor?

1. I also want to get a carrycot for the newborn. I think it's called the cocoon? Where does that go when the toddler is on board and do I just buy the cocoon or do I need some kind if adaptor too?

Thanks in advance if you're able to help!

I should say its second hand, approx 4 yrs old, if that makes a difference to what I need to buy..

no idea about car seat. I didn't think you could have a car seat on when using it as a double.

with the cocoon you have the main seat flat and the cocoon goes in there, held in place by the raised end of the flat seat. The second seat then sits on the top.