Possibly some large eye screws and wire wrapped around to hold them up.

depends on what the ceiling is like, but I was thinking wire, too

We actually did this in my daughter's room. We put cup hooks in the ceiling in various places where the branches would rest, then we wired the branches to the hooks....not tightly, but just hanging there. It worked for about 8 years, so I know it's safe. We didn't have any branches fall during that time either.

Depending what kind of walls and how big are the branches.

If the walls are of stud construction, anchor to the studs only. Use an electronic stud finder.

If the walls are masonry, use masonry anchors. There are many kinds. Ask the people at Home Depot. They will advice you.

dcarch

A commercial building usually has a suspended ceiling. Cup hooks and eye screws will damage the tiles and won't hold anyway. You can't put screws into the metal track because it will damage the track and cause it to rust.

You can loop fishing line around the ceiling track and put the eye screws in the branches. I did this for a holiday display and it worked very well. We used Origami ornaments and it turned out beautifully.

Before you go too far, better run this idea past the Health Dept. (or whoever does restaurant inspections in your area), the Fire Dept. and your insurance company. There may be liability or safety issues.
Sounds like a fun idea but better safe than sorry.

Yes - sounds pretty but I was also thinking you'd need to to check the fire regulations as it's a commercial building. They might not like the idea of dry wood and paper lanterns overhead.