Underpitched 1.084 beer. Will pitching more later help?

Hey all,
I pitched a Smack Pack of Weihenstephan yeast into a wheat beer (2.5 - 2.75 gallons) of a gravity of 1.084. It's got a pretty good Krausen-y head on it now (about an inch or two). I was wondering if I could off set some adverse effects of under pitching by adding more yeast after the fermentation head has reduced. I'd be concerned about the bubbly goodness preventing the new yeast from getting in there. Should I pitch more? If so, should I pitch the same yeast strand, or would Nottingham's be sufficient?

The downside of underpitching is that there are not enough yeast cells to efficiently handle the sugars in the wort. The yeast then get stressed and produce esters/phenols during active ferementation.

So adding additional yeast after the most active part of fermentation won't fix anything. The underpitched yeast colony already reproduced to an adequate colony size to finish the beer, they were just stressed along the way and already produced the esters/phenols .

Don't re-pitch, just let it ride at this point. You are lucky that this happens to be a wheat beer, as the esters/phenols the Weihenstephan yeast produce are usually desireable (banana/clove flavors), so the extra off-flavors you produced from underpitching are very likely to compliment the beer style.

In the future, though, follow proper pitch rates by making starters the day before brewday if you are using liquid yeast.

If you wait, it won't matter. It may not matter now - yeast need oxygen to reproduce, and that may already be used up.