In 1537 Henry finally got his wish, a son and heir had been born to Jane Seymour. He was named Edward. Though the succession now seemed secure and Henry was finally happy, tragedy would strike yet again. Jane Seymour died of childbirth complications twelve days after the birth. He now had a single baby son and two illegitimate daughters. He would have to marry again to secure the succession with a second son. In fact, he would marry three more times after Jane, but Edward would remain his last child.
The First Succession Act had removed Mary from the succession and the Second Succession Act had removed Elizabeth as well. The Third Succession Act from 1543 confirmed Edward as Henry successor, but also returned both Mary and Elizabeth to the line of succession. They would be behind Edward, any of his children and behind any children, Henry and his last wife Catherine Parr would have.
Mary and Elizabeth would remain illegitimate making their true place in the line of succession a bit unclear. However, it must have been somewhat of a relief for Mary. She too believed Edward was the true heir, but she was certainly in line after him.