How to preserve anonymity within Ripple?
Note, anonymity isn't a design goal for ripple. Depending on the level of pseudo-anonymity required, gateway and future features of Ripple would likely be easier (and more cost effective) than using many Ripple addresses (aka Ripple accounts).

To tell if two (or more) Ripple addresses are in the same family you need the public generator (which is named for generating the public keys, it should not be made public). Without that no one can tell if they are part of the same family and therefore they are funded/activated independently exactly like any other address is (someone sends it the XRP account reserve).

I'm not aware of any Ripple client that currently implements account families (the existing clients just use the public and private ECDSA key corresponding to index 0 within the account family).