Joseph
“We absolutely do. The b’chor will as a general rule get a double portion.”
I dont know how to tell you this bt you are not correct, IVe spoken to several Rabbonim including chasidish and yeshivish ones and they all said the yadvise people who ask to write a shtar chatzi zachor, to give girls equal to boys and that the bechor does not get pi shanyim (though some said the bechor should get extra).
you are right, that it is a major shailah, and there are people who do it in ways that arent chal.
I do suppose yo ucan argue that the mitzvah isnt being “avoided” since generally a token sum of money is left to be divided up al pi torah. See Ig”m CM 2:50 where he requires $1000 to be divided al pit torah. See also Minchas Yitzchak 3:135 where he struggles to defend the prevelant minhag of “ignoring” dinei nachla and gving inheritence to daughters.
“And Sephardim do Yibum.”
Are you sefardi? Neither am I. So WE do not do yibum. please stop hocking ah cheinek