I am not asking for a debate about changing the names of adopted children.
We do ot like those names an they would sound strange with our existing childrens names. e want them to fit in, an like other parenys, we want the joy of giving them their first gift - a name.
Yes I see you want the joy of giving them names. But you adopt those children, adoptive children come with a past and their name is part of that. It's about them, not about you wanting to name them.
You could change Oleg to Alec, I think that isn't a huge difference and an Alec would fit in. So, if it really is about them fitting in and not having weird names in their new country, you should go with that. Olga could go by Ollie.