Congratulations on your daughter's upcoming nuptials ...
Might consider a remix of the old classic by Elton John, "Your Song", done by actor Ewan McGregor on the original motion picture soundtrack for "Mouline Rouge".
Lyrics:
[And you can tell everybody this is your song
It may be quite simple but now that it's done
I hope you don't mind
I hope you don't mind that I put down in words
How wonderful life is while you're in the world
I sat on the roof and kicked off the moss
Well a few of the verses well they've got me quite cross
But the sun's been quite kind while I wrote this song
It's for people like you that keep it turned on
So excuse me forgetting but these things I do
You see I've forgotten if they're green or they're blue
Anyway the thing is what I really mean
Yours are the sweetest eyes I've ever seen]
This is a shortened version of Elton John's original, and leaves out the first two verses, which are:
[It's a little bit funny this feeling inside
I'm not one of those who can easily hide
I don't have much money but boy if I did
I'd buy a big house where we both could live
If I was a sculptor, but then again, no
Or a man who makes potions in a travelling show
I know it's not much but it's the best I can do
My gift is my song and this one's for you]
These two verses lean toward a bf/gf relationship, so its exclusion appears to be more geared to your needs.
Ewan McGregor does a very decent version on vocals, and he is accompanied by Italian tenor Alessandro Safina.
Another suggestion would be Carol King's "Now and Forever" ...
Lyrics:
[Now and forever, you are a part of me
And the memory cuts like a knife
Didn't we find the ecstasy, didn't we share the daylight
When you walked into my life
Now and forever, I'll remember
All the promises still unbroken
And think about all the words between us
That never needed to be spoken
We had a moment, just one moment
That will last beyond a dream, beyond a lifetime
We are the lucky ones
Some people never get to do all we got to do
Now and forever, I will always think of you
Didn't we come together, didn't we live together
Didn't we cry together
Didn't we play together, didn't we love together
And together we make up the world
I miss the tears, I miss the laughter
I miss the day we met and all that followed after
Sometimes I wish I could always be with you
The way we used to do
Now and forever, I will always think of you
Now and forever, I will always be with you]
Previously mentioned suggestions "Dance With My Father" (sweet but sad, involving the death of the father and sadness of the mother) and "Butterfly Kisses" were also good ones.
BTW, I skimmed over a couple of thousand soft rock/mellow rock/ballads/love songs (I collect these), and as you stated, there are not a lot of songs that depict a paternal/maternal love versus a romantic love.
Good luck in your song choice, though.