Final answer:
Lavinia first asked her mistress for help to publish Emily's poems.
Step-by-step explanation:
Lavinia first asked for help to publish Emily's poems from her mistress. With her mistress's assistance, she prepared her book for a London audience during her stay in England.
Wheatley had a high degree of authorial control over her work, editing the galley copy and improving the printer's proofs before returning to Boston.