I have several rooms with existing 6" solid hickory floors. We are combining rooms that have tile now and also this hickory flooring. Can we integrate engineered hardwood with the solid hickory where tile used to be and where interlacing may be required?

Solid hickory is usually three-quarter inch thick. Engineered flooring is usually five-eighths inch thick, although some three quarter inch thick engineered flooring is made. The T&G may not fit together.

even if you can they probably wont match and will look like a repair. best option would be to put in a header strip