If the arvo sleep is 'easier' then maybe start trying something different there. Take her for a walk or try a new stories & cuddles to sleep routine (or whatever you think might work). It'll probably take longer at first, but hopefully she'll get used to it before baby gets here.
DS is up at 5-5:30 most mornings, hungry. It doesn't matter how long or what time he naps, or when he has dinner...
For bed time, could you try bringing everything forward a bit? I'd just let her sleep in the arvo too.... I not it's not worth waking DS anyway - it makes no difference to the bedtime or wakeup time.