Hi Karen,
I didn't have a feeding tube so others will answer that one for you.

I would not assume anything is "normal" - you are then taking direct responsibility if it is not. Always consult with a doctor or if you have an oncolgy advice nurse, all the better. It sounds to me like your mother-in-law will need a caregiver. I honestly couldn't even imagine going through this alone. As I got more into treatment I got increasingly more helpless and dependent on my wife. Always ask the doctors for explicit instructions and/or complications to watch for - take detailed notes or tape record it.

I need to ask this - why is she taking morphine? Is she in treatment? What stage of treatment?

Assuming that she is in treatment and needing long term pain management:

Managing potent drugs like morphine need to be carefully done. If she were to do the opposite scenario, she might forget she took them, double or triple dose and OD. She shouldn't have to be waking up in the middle of the night to medicate anyway. Morphine is a fast acting opioid, typically prescribed for occasional breakthrough pain. Breakthough pain is caused by specific events such as eating or drinking. I never had to use a breakthrough med in the middle of the night. Some people have weird reactions to morphine also so keep an eye out for that.

It sounds like she needs to be on a long term opioid such as Fentanyl (AKA Duragesic). It is a 72 hour time release patch and fairly brainless to use. They can keep increasing the patch strength until the desired pain masking is achieved. And better yet, there is nothing to swallow or get stuck in the PEG tube - it also can't be vomited out.

Here are the NCCN cancer pain management guidelines:

http://www.nccn.org/professionals/physician_gls/PDF/pain.pdf

There are always constipation issues with pain medications so those eventually will have to be managed also.