Return to Work From Maternity Leave

Hi,

We are a small company and have tried to be as flexible as possible when considering return to work from maternity leave requests.

One request that we granted was for someone to return from 5 days to 3 days on the same pro-rata pay and bens and then after a subsequent return from her second maternity leave in June, to come back for 2 days.

Since the first request our business has changed and there is now a requirement for senior employees to travel with work, we are therefore finding that we are struggling to manage the workload as our part time employee cannot do it.

We now have someone else on maternity leave who has the same role as our part time employee but on a full-time basis and we are concerned that should she request part time, we would struggle to accommodate it.

Are we entitled to refuse the request, even though we have granted it in the past to someone else?

Also, if we do offer flexible working, can we alter her pay and bens in recognition that she will not be able to fulfill the role in it's entirety?

Thanks in Advance.