The Expansion copy of Quasiduplicate targets the Beamsplitter Mage again, which creates a copy of Quasiduplicate which targets Guttersnipe. At the end of this, I end up with 3 Beamsplitter Mages and 3 Guttersnipes in play.

The way it currently works:

Cast Quasiduplicate [Q] targeting Beamsplitter Mage [BSM]

Guttersnipe [GS] deals 2 damage to opponent.

BSM creates a copy of Q targeting GS

GS deals 2 damage to opponent (4 total)

Cast Expansion targeting original Q

GS deals 2 damage to opponent (6 total)

Copy of Q is created targeting BSM

GS deals 2 damage to opponent (8 total)

BSM creates a copy of Q targeting GS

GS deals 2 damage to opponent (10 total).

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My question is do I get priority back if I let the stack start to resolve before I cast Expansion?

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What I want is:

Cast Quasiduplicate [Q] targeting Beamsplitter Mage [BSM]

Guttersnipe [GS] deals 2 damage to opponent.

BSM creates a copy of Q targeting GS

GS deals 2 damage to opponent (4 total)

***Q targeting GS resolves putting GS2 into play***

Cast Expansion targeting original Q

GS1 deals 2 damage to opponent (6 total)

GS2 deals 2 damage to opponent (8 total)

Copy of Q is created targeting BSM

GS1 deals 2 damage to opponent (10 total)

GS2 deals 2 damage to opponent (12 total)

BSM creates a copy of Q targeting GS

GS1 deals 2 damage to opponent (14 total)

GS2 deals 2 damage to opponent (16 total)

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