Help with converting extract to all grain

For the DME/LME, assuming it was light/extra light extract, use 2-row or a Pale Ale Malt instead. You'll need to adjust the weight depending on the PPG of the grains and your mash efficiency. If you enter your original recipe in some brewing software, then start making the substitution, you can dial in the right weight for your base malt to get you to the same OG.

For the rest, use the same amounts. Or possibly use a little less of the C-20, because you may extract more stuff from it than when you were steeping it. I probably wouldn't reduce the Carapils though, because your extract probably already contained a little bit of that, and your 2-row/pale ale malt won't.

If you were already doing full boils, then I wouldn't change the hop amounts when going all grain.

ETA: for a wedding beer, I'd suggest at least three trial runs, and either tweak as needed along the way, or if no tweaks seem to be needed, ensure repeatability.

If taking kegs to the reception, be sure to not have a full tank of CO2 or a backup tank. Just kidding, but people seem to do that all the time with wedding/picnic/special occasion beers. OTOH, I go probably overboard, taking a backup regulator and a small toolbox of kegging tools and corny keg spare parts.