The Toy Soldier & The Ballerina

Twin brother and sister find each other's childhood toys when they visit their childhood home. Orphaned at a young age, they have only scant memories of this home which has been held for them in trust until their 21st birthday. The toy soldierand the ballerina transport them to an alternate universe where they embark on a completely different life. Where will they end up? In the real world or in their alternate world?
Think Indian in the Cupboard meets Narnia meets Outlandet meets that other book I can't remember the name of about the modern woman and her nobleman timetravelling lover from a medieval time