I'm not sure what medical assistance insurance your mom has, or what medica is ..
but I can give you a bit of information as to what MY mom's long term care
insurance pays, and how it is handled.  

Basically, in order for the private insurance to put in force (to make payments)
your mom has to meet certain requirements.  In order for the insurance company to
make sure these requirements are met, mom needs to be certified by someone ... a
nursing home, or someone that the agency deems qualified to make that assessment.
There were a specified 3 out of 5 things that mom needed assistance with, in order
to be approved for payment dispersement.  I don't remember what all they were, but
it was very difficult to meet those requirements.  One was needing assistance to
go to the toilet, one was bathing/dressing, one was feeding ... I think another
was getting in and out of bed, and I don't recall the fifth.  Cleaning and
household help, financial assistance, memory problems, etc. did not fall anywhere
within their standards - it was all self help independence type things.  If three
were not met and certified, payment would be denied.  You can lay it on thick, but
those PHN's are not fools either - they know what to look for, they deal with it
all the time - and more than likely have also dealt with those trying to beat the
system (which make it harder for those like you who are trying hard to make it
work).  So don't overdo it, it may possibly make things even harder.  Try to keep
everything within the realm of reality.  Since you have 2 weeks before the PHN
arrives, I would suggest you keep a daily diary of exactly what you do and when
you do it.  Don't stretch it, don't exagerate it.  Taking 30 minutes to give
pills, an hour to get dressed is going to raise some eyebrows. <grin>  I know my
mom needs total assistance getting dressed, yet she cooperates and the chore only
takes a few minutes (maybe 10).  Let them see over the course of 2 weeks how
varied the days are - there are good days, there are bad - these people are used
to this and will take it all into account.  Again, just my opinion on things -
with what I have seen and dealt with regarding the insurance companies and
certification.  The last thing you want to do is make things even more difficult
for yourself.  Once a question is raised, it will be hard to get them to
re-evaluate their decision or change their minds.

I'm not so sure about your POA sister not having to approve it though.  They may
not need her approval, but someone has to sign the forms each year (at least for
my mom's insurance) and it has to either be the patient themselves, the POA, or a
legal guardian.  No other signature is accepted by mom's insurance carrier.  And
mom has to be recertified yearly (rechecked) and forms must again be signed and
filed before any further payments are continued.  I had to have the POA on file
with the insurance company, as mom can no longer sign her name.  If your mom is
willing to sign the paperwork, there shouldn't be a problem.  If she isn't, then I
think you may need your sisters cooperation in filing the necessary paperwork.  Or
you will have to have yourself legally declared her guardian - which is another
matter altogether and your POA sister could fight you on that.

If medica is similar to medicare, they will not pay for nursing care in the
private home.  They do pay for nursing home care, again - with restrictions and
only for a max of 90 days.  It was explained to me last year, some of which I have
forgotten or just too difficult to explain.  It kind of boiled down to *have to
have a medical reason for the nursing home, have to show need for the treatment,
and have to be able to be showing an improvement from said treatment*.  In
otherwords, they won't pay just to have you there, even if there is a necessity.
Private in home nursing does qualify for payment, but again - very short term and
I believe it has to be medically ordered by a physician - such as home health care
immediately after a major medical issue (stroke, heart attack, rehab, etc.).
Unfortunately, dementia/alzheimers seems to fall through the cracks.  

As far as why your insurance company requires an agency that has a contract with
medica, I have no idea.  It might just be one of those restrictions set within
their policies.  It could also be that an agency who is under contract with medica
must meet certain requirements with their employees?  I know for my moms insurance
policy to make payments, the nursing home has to meet certain certification
requirements, as well as providing a licence.  Since you are requesting private
payment, as an employee of a specified agency, then this agency would have to meet
similar requirements.  It's probably a protection measure for the insurance
company as well as the patient.

My answers/explanations are based solely on my own experience, with the long term
care insurance carrier my mom has.  Each company may have different requirements
and terms.

Joyce