I have been a steparent to two children for over 10 years who are now 19 and 20. It has been a bit tricky over the years - issues with accepting me as a new partner, being seen as the blocker to the possibility of their parents reconciling and general teenage struggles and conflict "you are not my mum". In particular my step daughter struggled with the fact we went on to have two children of our own and we married. Their mum and dad have done a great job of putting their issues aside and being excellent co-parents. I have tried to be the best step parent I can be but I admit to have found it extremely hard sometimes and felt that what i wanted always came last .....but today - I see all of the children running about in the garden together having fun - the younger ones idolise the older two who really love them/cherish them. My SK's confide in me and share things that are personal to them - they are very good company. On my Birthday they sent me a card that said thank you for being the lovely you and taking care of us. It made me very happy.
So for anyone struggling - it can be hard but it won't be forever 
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