transferring a mutual fund from one broker to another does not change its tax basis. how can you properly report their basis, except using specific identification, since you don't seem to know the basis for the earliest shares acquired? didn't you statements from the previous broker properly reflect the tax basis.
guidance is provided in IRS PUB 550 starting on page 67 as to allowable methods
https://www.irs.gov/pub/irs-pdf/p550.pdf
