By default (that am seeing) , clients under branch offices will not get proxy management info unless you add the boundaries of branches into boundary group with mp defined .
Lets take ex: I have lot of branch offices in location that has secondary site with MP,DP,SUP (a.ak. proxy MP) .So when i create boundary group for these branch office boundaries ,i do not specific the MP info in site system tab ,because i do not want my branch office clients to download the content from sec site which is DP and also MP. In this case ,i have not defined my MP info hence clients will always talk to primary site MP for policies etc and never be secondary site MP (proxy). To fix this ,i need to edit (though unsupported) mpgetproxymplistforsite stored procedure to get this fix. The default SP MPGetProxyMPListForSite will not work .

Can we get this MP_GetProxyMPListForSite changed for the next update release ?

Regards,
Eswar