This extra tissue will eventually stop producing milk.
It's not related to the rest of her glandular tissue, as each section of the
breast may function fairly autonomously according to recent data from Peter
Hartmann in Australia.
She'll involute there if there is no outlet, while the rest will produce milk
- the autocrine feedback is what controls ongoing milk synthesis, not
primarily the prolaction response.

Sounds like another galactophobe's alarmist scare tactic to me.

Linda Smith, BSE, FACCE, IBCLC
private practice, Dayton OH