Hi,
I'm in a similar situation- I'm 20 weeks tomorrow with twins, and DD will be 18 months, hopefully nearly 19 months when the twins are born. I have just bought an ABC everest as recommended from on here, with the reclining seat for a tired DD just because the seller had in-laws near us and said they'd deliver (though not heard from him since we bought it
). I wanted a side by side double for my twins, so couldn't have a bike attachment or anything as it makes it as wide as a side-bu-side triple so not practical for manoevering, and to go in shops was told really 2 is the lower age limit for actually standing on a buggy board nicely... And I could see my DD at 18-19 months not using it well. If you have a tandem, you can use a bike attachmant, or maybe a buggy pod for your DD. I can't do fancy links, but here they are:
www.kiddicare.com/webapp/wcs/stores/servlet/productdisplay0_10751_-1_95826_10001
and
www.bambinogoodies.co.uk/bibi-buggy-bike/
I looked into it a lot, and thought about just using the sling, as I carried DD til she was 9 months, but carrying one and pushing two, and stopping in the rain to get the baby out of the sling to put a rain suit on and back in, etc etc convinced me to go for the Everest ABC as they re-sell really well on ebay from what I've seen (I watched a few to have an idea of outlay, before splashing out way too early becasue of said delivery option...)
We will move to a people carrier to fit the monster buggy in. I also have DD in an extended rear facing car seat, the BeSafe iZi Combi, aka the world's largest car seat so anything else not going to work for us!!!
I am so, so delighted to be having twins now, and terrified somethign will go wrong. Hence why I am still up on the internet, not in bed, as I have my 20 week scan tomorrow and I'm worried abou it! I feel very blessed though, and really, really looking forwrad to them arriving! Hard as it will be...
Where are you based? I'm North West