yes sardine i too am confused by the comments regarding 'innappropriate' and the need for 'boundaries' they are 3 and 5, there is NOTHING sexual or innappropriate, its simply too children imitating their mother, its one of those things that children do and as for when they would be 'too old' to carry on doing it, i suspect that they will have grown out of it long before i 'may' become an issue.
bluefergie i echo others, your children sound delightful, they are playing, its sweet and i wouldnt worry about it, IF you do feel that youare worried of a reaction you could do what one poster suggested earlier (forget the name) but it was about saying something like 'does baby need a burp now' etc and so simply moving the game on to the next stage of the feeding process! very simple, you are engaging in their game and it will distract without any need for explanation.
but they will grow out of it, my ds1 used to 'feed' his toy teddies and dolls etc, he is now 12 and i cant begin to remember the last time he did that, he laughs when we talk about things he did as a baby/toddler and as he had 4 younger siblings he knows its all normal, he also has a healthy attitude towards his body etc and knows that breasts are to FEED babies, so when we have been out and about and seen people bfeeding he doesnt bat an eyelid, to him its just NORMAL,this is what we want our children to grow up knowing :)
btw i have a magnet on my fridge that says 'doing the housework whilst children are growing, is like shovelling the snow whilst its still snowing' ;) enjoy your little ones xxx