Here's my first thought... What you have in the 3 acre pond, will also be in your new bigger pond. Fish will over flow out of the 3 acre pond in high water events and thus will end up in the bigger new pond. So keep that in mind when planning fish communities... You will have LMB, BG and crappie in your new pond, there is nothing that can be done about that...

YP and WE can survive in ponds with the above mentioned species. Take some time to utilize the search feature of the forum and type in things like walleye/WE, crappie/BC, etc... There are piles of info about those species and any others on here. Some very good recent threads.