(Image credit: Getty Images) Most grandparents think of gifting in terms of birthday checks or holiday envelopes. But for those looking to make a transformative impact, the real opportunity lies in "seed capital." By leveraging specific IRS rules — such as funding a custodial Roth IRA to jumpstart decades of tax-free growth — you aren't just giving money; you are giving the gift of compounding. By initiating these strategies while your grandkids are young, strategic gifts can effectively "fund" a child's most significant future milestones. How well do you know the rules governing these sophisticated wealth-transfer tools? Take our 10-question quiz to see if your current strategy is maximizing the legacy you intend to leave behind.…