It can be very difficult to merge families. Even if there are few kids involved, not everybody w8ill always mesh together, and it can take some time for someone to become comfortable with having a new guardian figure around. At what point are you meant to take orders from this mysterious new person? Do you have to eventually stop calling them by their first name? Every family eventually develops its own dynamic and as long as there is mutual respect things should go pretty smoothly.
But when somebody prances into another person's home and begins making orders based on their own beliefs, things will probably get messy. Good luck making friends with your new teen step-daughter after telling her that her 'women's products' make you uncomfortable. As if having a period is something that should be hidden, or not spoken about in any capacity. This young woman was told to hide her packaging from her new 'dad' and it did not go over easy.