Honesty is always the best policy. 

Your reasons for changing are probably the best I can imagine. If you don't say why you want a change, they may jump to less charitable conclusions.

If you already know what hours you will be expected to work, you could explain that you need a job which enables you to visit your sick Mum every evening/morning/whatever time you visit.

If I was interviewing you, I might ask follow up questions about whether there are any specific times of day that you cannot be available?  

You might want to ask why the post is being advertised as part-time, is it part of a job-share, or are they busy at a particular time of day? One of the most common reasons I used to advertise part time posts in my own NHS department was to fill in gaps in staffing levels due to school/child care timing issues. Many new parents are unable to return to work full time, so we'd work up job-sharing arrangements with people who preferred not to work between 10am and 3pm. 

Good luck with the interview
Dave   

Thank you, I've always believed honesty is the best policy. And my current employer has been less than supportive at times which has pushed me to look else where. 

How do I approach the subject if the question leading to that discussion doesn't arise? 

Most interviews end with the question "do you have any questions for us?, I'd drop it in there if they haven't already covered it.

Hi

Though I stayed put when my husband was diagnosed,I was honest from the start and eventually reduced hours to be able to cope.  Think Dave's response would be the best policy and wish you the best of luck when you go for interview.  Jules

Thank you. I would stay where I am but they have been rather unsupportive and at time down right cruel!! When I explained I would be assisting with my mums care I was told I should just put her in care and be done with it!!

I have been told in no uncertain terms this reduced hours are temporary & even now when it comes time for me to go home there's always a problem with it. It's sad really I've been there many years and even though I've been treated poorly throughout my time I thought when I really needed it they would come through, I can't believe how wrong I have been :( 

The stress from work has given me anxiety attacks & stress related hives, I can't and I won't continue to go through this anymore, I feel as though I am agreeing with their views on how I should handle my situation by staying. 

Hi

It is so hard when long term employers cannot seem to have compassion when someone is facing such difficult times/decisions within the family.  I am sure you will do what feels right for both your Mum and yourself and hope you have other friends and family support along what is a hard journey at the best of times.

I certainly found it helped to write my feelings down here on the forum and welcomed the support I found and still find here. Sending virtual hugs and hope the interview goes well.  Jules

So sad that you are feeling this way when you are also obviously so worried about your Mum.  I am sure your Dad's words were not meant to upset you and that he too his feeling such emotional pressure he does not know how to deal with his own feelings either. My husband withdrew more and more into himself when he was ill and so I found it hard not being able to have an open conversation but maybe the very person who could help you here is your Mum; even a hug with each other can mean so much and do not be afraid to ask her for one or give her one back for that matter if that is a possibility.

If you are in the Uk you could try giving the nurses a ring on this forum and chatting through your fears and feelings as regards coping with your Mum's caring role alongside employment worries and maybe your own GP could advise on help for your own anxieties.  I can imagine you are feeling pretty miserable about everything but hope you can find that little bit of inner strength to get through the interview.  I have not been for one for years and think it perfectly natural to be 'quaking on the inside' so hope you have reason to go after what you would really like.  Wishing you, your Mum and family all the best at this difficult period.  Virtual hugs.  Jules