Hi Enahsss
Yes, you will be placed in the same room. You can select bottom / middle / top because in the sleeper cabin with 6 people there are 2 beds on each side, so 2 bottom 2 middle and 2 top.
If you select bottom as a preference then you will most likely get 2 bottom beds as long as 2 are available in the same room. If not, then just one person gets the bottom one and the other gets the top.
Hope this clears some things up. Best regards
Zebis