Hi there and welcome to BW
I think you have to be a bit creative when it comes to timing naps when you have another LO and a school run giving unavoidable pram naps etc. You might find some additional tips on the twos board:
http://babywhispererforums.com/index.php?board=20.0The 45 min naps are a sign of UT (under tired), you're right about needing to extend that A time.
http://babywhispererforums.com/index.php?topic=64158.0When they are used to going down for a nap at a certain time or a certain A time a habit is formed, their body clock will continue to tell them it is time for a nap then even if they haven't really been awake long enough to get fully tired (tired enough to transition into the next sleep cycle and have a longer more restorative nap).
I suggest moving the A time up gently, with some low key activity if possible, maybe just cuddling, looking out of the window together or a stroll around the house for an extra few minutes. If she is really cranky then take it slowly, increase 5 mins every 2 days. If she can handle a bit more then go up 10 or even 15 mins every 2 or 3 days. This slow increase will give her time to adjust. It will likely take several days for her to settle into the new A time but you should see an improvement in the nap length. I would work up to an A of 1hr 20 or 1hr 30
As for the school run. You might be able to start the nap off in the pram at the right A time before you go out perhaps? And let her take the full nap there leaving her in the pram when you get home? This isn't possible for everyone, it depends on your circumstances.
If you cannot offer a longer nap then it is perhaps going to work around the family commitments better to keep the first A short so that the first nap IS only a short one.
As she gets used to a longer A time you might even find you can get home before the first nap (not always possible as the motion of the pram is pretty sleep inducing), this moves the nap later in the day and if the nap extends to a good length or 1.5 or 2hrs you might then be able to do the 12pm school run and get back home before nap 2. Your morning might then look like this:
WU 7.00
A 1hr 30
S 9.30 at home in cot 1.5hr/2hr with WU 11.00/11.30
A 1hr 30
S 12.30/1.00 1.5/2hr with WU 2.00/2.30
That's just an idea of something to work towards, I'd advise against jumping straight to this if you LO is crying with longer A times, go slowly and you will likely have more success.
Extending in the pram, most LOs will continue to sleep if in motion, we usually call this AP or APOP (accidental parenting on purpose), when you have another LO to care for you can't necessarily get all the naps in the cot. If possible I would aim for getting one nap per day in cot so that a cot napping habit is formed as soon as possible. This will help in the months ahead.
hope this helps some x