Krausening to fix diacetyl

I have a vienna lager fermented with Wyeast 2124 bohemian lager about 2 weeks into lagering. I did a d-rest but my hydro was off by 5 points and I think it was too late--lots of diacetyl. I'm going to try and fix it by krausening in some fermenting wort and was hoping for some feedback.

What sort of volume will I need to krausen into a 5 gallon batch to clean it up? So I'm thinking a 1-2L starter of either kolsch or bohemian pilsner and pull it out of lager to 62F for a few days. Alternatively I think my next batch might be a mild so I can pitch some of that in, probably also with the kolsch. Other concerns or methods of fixing it? Thanks.

A quart will be (should be) sufficient-make sure to vent often, if in keg. I would make a starter with the same yeast used originally if possible-if not use a neutral yeast. I would think more yeast.....smaller volume of sugar-so the yeast quickly get to work on the diacetyl.

I still have a slant of the 2124 I can build up, I just wasn't sure if a kolsch yeast might be more aggressive in cleaning up the diacetyl. I'll give the 1L starter a shot. Does 62F sound right for the D-rest?

I am sure any yeast would work for clearing up diacetyl. However. We have to remember we are adding back wort with simple sugars from which the majority of esters are created. At 62 pick a yeast that can stand 62 prob a lager yeast and pitch about a quart. I am thinking that at 62 maybe a larger starter at a later stage in its cycle mid to late krausen. Remember because you are adding the whole starter you want the starter to be similar to your current beer. My reasoning on adding a later stage starter is that this will mimic the wort from when the rest should have originally been performed. Let me know if ya have other questions. Either way you will get rid of diacetal. The differnces in methods would be minimally noticed if at all.