Complex sentence: In 1933 the group got involved in the Suriya-Mal Movement, which had been formed to provide support for indigenous ex-servicemen by the sale of Suriya (Portia tree) flowers-at the time Poppy Day funds went solely to British ex-servicemen.
Split into simpler sentences: In 1933 the group got involved in the Suriya-Mal movement, which had been formed to provide support for indigenous ex-servicemen by the sale of Suriya (Portia tree) flowers. The Suriya-Mal movement surged as a reaction to the fact that at the time Poppy Day funds went solely to British ex-servicemen.