How to combine multiple objects?

[Spock]

Im trying to make a tunnel. A sci fi themed tunnel specificly. The vanilla game only includes the air lock tunnel piece so far that I have found.

Anyways just trying to use a bunch of those. Im trying to place the tunnel on the lift hill of my coaster to make it more exciting as that is the most boring portion. I know how to use multi select, however the move options are touchy with this and I keep having an issue with it deselecting all of them once I try to go to the fine axis movement, at which point the tunnel is over the coaster. Now multi select becomes useless as it will now also selects the entire coaster as well as the tunnels. I obviously dont want to have to place and angle each piece. The easiest thing would be to combine the tunnel pieces as a single object(not multiple selected) to where I can click once anywhere on the tunnel and it selects it all as a single piece. Is this possible?

[McDread]

This is possible - the thing that is confusing at the start is that you can only multi-select and copy scenery pieces that are attached to the same building model. If you place a wall piece (or anything that snaps to a grid) then place scenery pieces while still editing the building then you can ctrl left click multi select those scenery pieces and copy and re-place them using either free move or advanced move. Note that if you select the "grid" part along with scenery pieces you can only rotate it in one axis rather than all three (grid walls will remain upright). If you've placed a load of scenery pieces for a building but haven't used any of the grid pieces, simply add in a basic wall section nearby and use the multi select button (bottom right) to select this and the scenery pieces then click on the "add scenery to building" option (a little house with a plus next to it). Now the scenery pieces will be part of a building and you will be able to duplicate whole sections of it... Phew... Sorry for the wall of text, hope it helps - and don't be daunted, once you get it it'll make more sense!