Have 2 DCs and 3SDCs all teens.
Good relationship with eldest and youngest - am not their Mum, will not be spoken to like crap and I expect them to abide by the house rules as do mine, ie cleaning up, washing up etc etc. We have a laugh and joke and more an extra aunt relationship - it works.
Middle SDC quiet, moody, pushes the boundaries and adores Mum. It is just an uneasy relationship but it jogs along with no majorish issues.
Today I made cakes very rare for me! one chocolate for my DCS and youngest SDC - their favourite, one ginger eldests favourite and one fruit loaf - middle ones favourite.
We all sat down for tea and cake and the middle one glared, took a slice and another - then said FFS why can't you be a evil stepmother then I can moan about you - but even your fruit cake is bloody good!
I figure I am not all bad then - should have done this 2 years ago!