She was a member of the Melbourne Society of Women Painters and Sculptors and the Twenty Melbourne Painters Society Inc.[1] Tweddle was born Isabel May Hunter on 26 November 1875 in New South Wales.

[1] In 1904 she married Joseph Thornton Tweddle, an Australian businessman and philanthropist.

Tweddle visited Scandinavia and the Pacific (the Solomon Islands, New Guinea, and Japan).

[1] Tweddle had an interest in Post-Impressionist art, mainly though the work of Arnold Shore and William Frater.

[1] She is thought to have influenced Sybil Craig, Peggie Crombie and Jessie Mackintosh.