Q&A: On maternity leave and doing two jobs

My wife has two jobs. Her main role (job 1) and her part time role (job 2) are with different employers. Currently, she is being paid SMP from her main role and full pay from her part-time role, mainly because of her good working relationship and she is flexible with them in the sense she can still do some work from home so helps them out in that way. The first question is that she is now thinking about returning to work officially with job 2, but taking the full 12 month leave from job 1. Will this affect the SMP she is paid from job 1? We are worried that if she does this the SMP will stop or HMRC might ask for the SMP to be repaid, which we are not in a financial position to do. The second question is that her remuneration package for job 2 includes a basic salary and a bonus each year based on sales. That bonus is now due, but we are worried that when HMRC see this being paid through her payslip they might think she has another job full time and has no intention to return to job 1 (which is not the case, she will return at the end of maternity leave) and say she is no longer entitled to SMP from job 1?