Regex replace using a substring of the regex result value - regex

Question

I've been reading a ton of material and thought I had found my solution but no luck. I need to find apostrophes contained in a name and then replace them with a double. I am loading a file to an array and then looping through that, looking for the apostrophes. The catch is that each row can have several apostrophes so that's why it's not a simple find and replace.
Here is a sample of the file:
create(xxxxxxx)using(xxxxxxx)name('O'Doe, John')
replace(xxxxxxx)instdata('ab 1234 ')
create(xxxxxxx)using(xxxxxxx)name('Doe, O'Jane')
replace(xxxxxxx)instdata('ab 5678 ')
There are other lines inbetween but they don't contain apostrophes.
Here is what I have so far:
$Pattern = "[A-Z]'[A-Z]"
$user = gc C:\Temp\mfnewuser.ins
for ($i = 0; $i -lt $user.count; $i++) {
if ($user[$i] -match $Pattern) {
$user[$i] = [regex]::replace($strText, $Pattern.substring(2,1), "''")
$user | out-file C:\Temp\mfnewuser.ins
}
}
I'm looking for a capital letter, followed by an apostrophe, followed by another capital. Because of the other commas, I can't just do a global replace. I know my pattern matching is working but I can't seem to manipulate it with the substring. The substring looks at $Pattern as a string instead of the result of a regex. If I can save the regex result to a variable, that would be great. I think then the replace would be easy.
Tried this as well but no luck either:
$Pattern = "[A-Z]'[A-Z]"
$NewPattern = "[A-Z]''[A-Z]"
$f = Get-Content C:\Temp\mfnewuser.ins
$f = $f -replace $Pattern, $NewPattern
$f | out-file C:\Temp\mfnewuser.ins
I may be approaching this all wrong and there is an easier way but I haven't seen anything yet.
EDIT:
Based on Bill_Stewarts example below, I've got this to work on the First Name but not yet the Last Name:
$Pattern = "[A-Z]'[A-Z]"
$user = gc C:\Temp\mfnewuser.ins
for ($i = 0; $i -lt $user.count; $i++) {
if ($user[$i] -match $Pattern) {
$user[$i] = $user[$i] -replace "(.*[A-Z])'([A-Z]+.*)", "`$1''`$2"
$user | out-file C:\Temp\mfnewuser.ins
}
}

Answer 1

Perhaps something like this?
get-content "test.txt" | foreach-object {
$_ -replace "([A-Z])'([A-Z])", "`$1''`$2"
}
Regular expressions can be grouped using ( ) and the -replace operator supports substring replacement ($1 and $2).

Answer 2

Replace your line, with the following.
$user[$i] = $user[$i] -replace "([A-Z])'([A-Z])", "`$1`''`$2"
Or try one of the following. This should suffice.
get-content "mfnewuser.ins" | foreach-object {
$_ -replace "([A-Z])'([A-Z])", "`$1`''`$2"
} | set-content "mfnewuser.ins"
...
get-content "mfnewuser.ins" | foreach-object {
$_ -replace "([a-zA-Z', ]+)'([a-zA-Z', ]+)", "`$1`''`$2"
} | set-content "mfnewuser.ins"