Anyone with Partigyle Recipe Formulation Experience?

I'm looking to start doing a lot of Partigyle's on my brew day, in which I form recipes around the small beer, rather than just making big beers and taking what I get as a second beer. So in other words, I would scale up an English bitter to make a nice barleywine with the first runnings instead of HOPING to make a nice bitter out of the second runnings from my barleywine... If that makes sense.

My question is, how do I scale up the specialty malts? Or do I at all?

For example, lets say I was trying to make a bitter like "no short measure" from "Brewing Classic Styles". That recipe calls for 89.1% English Pale, 7.3% Crystal 120, and 3.6 percent special roast...

To make a first runnings Barleywine based on that, would I just scale up the base malt until I hit my target OG for the barleywine, or would I also need to scale up the specialty malts?

I know with an Imperial you would normally just scale up the base malt, but a partigyle is obviously different and I'm not sure how much of the flavor contribution of the specialty malt will be reduced if I just scale up the base malt. I'm a little lost on this one.

Anyone have any experience here? What would you do?

I have been doing semi PG brewing for the last year or two. I do 10-gallon brews because I don't get to brew enough. 10-gal. of one style of beer is more than I care to drink. I am not real keen on barleywines or most high grav. beers so a HG and a lighter grav. beer of one style doesn't work for me.
Mostly, I have been mashing an 11(+/-) gal. brew and dividing the mash into (2) 5-gallon brews. I have been steeping some specialty grains and adding them to the sparge to end up with 2 different 5-gal. batches. Depending on how I split the sparge I can end up with very different OG's on the two beers. And with different yeasts I can end up with 2 very different beers. I have done some Scottish Ale/ESB brews; IPA/PA brews; ESB/Stouts; ESB/Irish Red ales. You get the idea. And for a little extra time in the brew day I get 2 different beers.
When I was starting I used Beersmith and from the 2 recipes I would add the OG's and make a new recipe with the combined OG. It took some tweaking and I still haven't perfected or streamlined the BS side of the brewday. (I am always going back and forth between the 11-gal. base recipe and the 2-sub recipes. If it is all the same beer I would try designing 2 recipes and then combine the grain bills and volumes in a third recipe. Good luck with your PG.
I just saw you are from NZ. Go All Blacks!!