Vertical Nail Lamination

[Riggers]

I am planning to build a workshop under my house (It's elevated at the front, virtually double storey with nothing but open space underneath, I don't know why the original builder didn't make use of this space but they didn't so I will - probably cost restraints during the 1950's I guess)
The plan will of course require removal of existing stumps and replacement or additions to the existing bearers, to cut a long story short I have consulted the Vic Timber Framing Manual which suggests that for the required span what is needed is two 190 X 45mm F17 seasoned hardwood members vertical nail laminated.
My question is - Can I leave the existing bearer (circa 1950's, was originally F7 unseasoned I guess but by now is probably F3000 because I can't drive a nail into it without pre drilling!) and nail laminate one F17 either side of this existing bearer and maintain the same structural integrity as two F17's laminated directly to each other?

I know this is a sort of long winded question but this is my first forum venture
Thanks

[ausdesign]

Yes, as long as the new 'bearers' have the required end support.

[DvdHntr]

You are too helpful Ausdesign. Keep answering the questions before I can. What he said.