Tabbed Website (multi-brand/multi store), But use different shopify accounts?

[SemiBryan]

So we have a couple separate websites under different domains and urls, thus resulting in having separate Shopify accounts for each (we are on Shopify+). But we are considering building a new website to aggregate all our current other websites into one, much like what GAP did here. 

But what we are wondering is if it is possible, is that we keep all our separate websites and separate Shopify accounts up and live, and this new aggregate website (with branded TAB header) has all its product info/data/inventory/pricing pulling from the single Shopify accounts (so we don't have to manage this info in more than one place), and this aggregate website to have a single cart/checkout, but when an order is placed the items within that order create separate orders within each of the respective Shopify accounts/brands. Is this even possible?

We want it so that this single aggregate website, the customer can shop between the TABS (of each brand) and add items to cart from any of the branded TABS and checkout only once. But when the order is processed into Shopifys portal, it then creates separate orders into each branded Shopify account only for those specific branded items. Does this make sense? 

[Tamara_Gates]

did you ever get an answer to this? we have the same question