The IRS does not publish information regarding exactly how they make the final determination of how much of a refund is allocated to an Injured Spouse. The IRS has a formula they use to determine the refund based on your Form 8379 allocation of income, expenses, deductions, and credits between you and your spouse.
In your situation, since you are the main household provider, you should allocate all of the dependents to yourself (Injured Spouse) so that you get the highest allocation of the refund.