Elite, thank you for your response. I have further question, if you don't mind. I have been to several matress stores and the sales people say there is no problem with 2 twins. They say using matress covers and sheets will ensure 2 twins work. Is this their way of getting a sale at any cost? If so, No wonder sales people are often not trustworthy.

Trust me on this; a while back we stayed at my mother's 2nd home between selling our home & purchasing another. She had two twin adjustable beds that you would hook together & make a king bed. While the frames & box springs stayed together we were up & down constantly pushing the mattresses together & it was very uncomfortable to be toward the middle. We used both king mattress covers & sheets; we had to adjust them & refit them when we pushed the mattresses back together. This has been a while but would never do that again. Maybe it is different now but that is my experience.

Thank you so much, I really appreciate your advice. Cheers!

sorry but we've had two twin box and mattress sets in our king frame for over 20 years. the mattresses are so heavy they have never separated. it's a pretty common set up, not to mention easier to fit up stairs and landings. i'm getting swap out out our mattresses and frame for another set of twins, this time on an adjustable base.

We just replaced our bed with 2 twin xl (Tempurpedic adjustable beds) I
am bordering OCD so before buying, I am worried about the gap, I now
have it for 2 years now and my husband and I love it. He has his head
inclined which helped solve his snoring and we are both able to sleep
well at night. The mattresses are heavy for it to move about. I am a
small woman and changing the sheets are a lot easier than the single
king.