According to PipeDown :
Going from small to big won't cause much of a problem, aside from a "if
you draw too much from one faucet, you might suck air in another"
factor.

You would never suck air into a fixture unless for some very unusual reason
you were pumping warter out of another fixture at a rate greater than the
source can replenish it. Excessive flow at one fixture would cause a
reduced flow at all other fixtures on the branch since all are passively
powered by available water pressure. Only if a fixture were actively
accelerating the water would a negative pressure develop in the pipe to
cause air sucking.

Heh, no, sorry.

Take a two story house with heavily restricted water feed. Turn on a faucet
upstairs. Now, go turn on another faucet on downstairs.

Do you hear the faucet upstairs sucking air?

We do ;-)
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.