Ok, I must admit I thought this was a ridiculous question at first read. But I do know that MrDEB is working on a project with a bunch of MOSFETs on a board, so I understand this "we join this question in progress" question.....
MrDEB wants to know if he can attach 8 MOSFETs to a common copper area on a circuit board. The answer involves knowing what the tab is connected to. And actually, datasheets are surprisingly UNhelpful in this regard.
As far as my 4am brain and eyeballs can determine, nowhere does this datasheet actually say which pin is which or what's connected to the tab.
These two examples are better, showing the pinout but nowhere (again, blurry brain) do the datasheets explicitly state what's connected to the tab. If you're familiar with the TO-220 package, you'll know that the center pin connects to tab, but it would be nice if the datasheet confirmed that.
So, as stated above, pin 2, the drain, connects to the tab. If you want ANY MOSFET to turn on ALL the LEDs, this would work great!
But what you can do for some heatsinking is connect each MOSFET to an
isolated copper area. Make sure the footprint has a pad for the tab (i.e. no soldermask) and if you can include a copper area on the bottom of the board, stitch top and bottom together with vias.