I asked for floor standers because that's all I had and knowing that it was weird in the first place. However, with everyone's help including yourself, I opted out. Now based on the 1 of the 2 alternatives suggested by members here, youtube vids and international forums, bookshelves can be used for front heights for ATMOS. I prefer that route because not only my ceiling cannot accommodate floor standers the shape of it will note be able to handle in-ceiling speakers (masyadong maliit ang space in between wala pang isang dipa). Unless the space between the in-ceiling is acceptable baka pwede po yung in-ceiling as per your suggestion.
Pero tama po kayo sabi nga dun sa isang forum:
I feel that if properly positioned in-ceiling speakers give you 100% of the experience, well positioned height speakers will give you 90-95%, as opposed to the 70-75% of the best possible scenario upfiring speakers.
Thanks sir markcrenz. :-)