plastic water pipes

Hi
I have taken over a newly refurbed restaurant and i need to run water pipes from the main supply which is 15mm piping to 1. handsink. 2. commercial sink. 3. coffee machine. 4. Undersink water boiler, and a spare ready for a combi oven.

What i need to know is: can if i run feeds from the main pipe (15mm) to each one of the above by inserting an adapter tee joint which increases to 25mm pipe or similar, will this increase the water flow or will the 15mm suffice to feed all.

Hope this makes sense.