Generation vs Blood Potency question

me and my players were wondering about an aspect of Gen vs Blood Potency. It states on page 149 that caracter gen 10 gets 2 bp. we were wondering if the +1 bp that the Ancillae gives ups the bp to 3? If so why is it written on page’s 137 recap that 10th and 11th have bp 2. What a gen 9 sires a 10 in 2015… he would not be an Ancillae but would still get the base 2 bp right? I’m a french speaking person so I hope I’m clear lol Thanx a bunch