DD 'breastfeeding'

[BlueFergie]

Ok DD is 5 and DS1 is 3. They are great pals and play really well together. They play lots of role play games including mummy and daddys were they are the parents to a baby doll. Recently it has become mummy and baby with DD as mummy and DS1 as her baby. As part of this game DD will lift her top and pretend to breast feed DS he will put his mouth on her nipple and pretend to feed.
I know its not a huge deal and it's perfectly innocent of course. I am breast feeding DS2 so to them it is just how babies are fed, and they both always did it playing with dolls. But I don't know if its appropriate
DH thinks it isn't and needs to be stopped. What do you guys think. Should I say something and if so what.

DS2 and I have something of a post-bath ritual: I take him upstairs in his towel, dump him on the bed and then he crawls madly all over it, giggling, while the Mummy Monster chases him and bites him (gently) on his lovely, chubby and most importantly, freshly washed bum.

DS1 regularly 'breastfeeds' his 'cuddly friends' (soft toys) and it makes me come over all teary and unnecessary because it's so sweet.

My DS used to love being wrapped up in the towel like a "parcel" then carried somewhere - usually dumped on bed ! - to represent being "posted"/"delivered" - could then be "un-wrapped" - "Ohh, what have we got here ?" "A small boy, well I never !!"

My Mum used to do the same parcel thing with us ... Try it, it's a good 'un !