Can a grandchild who was financially dependent on a grandparent bring a support claim against the estate?

It depends on whether the grandchild fits within Part V of the SLRA's definition of a dependant, which centres on the deceased's spouse, parent, child, or sibling — and Part V's definition of "child" already expressly includes a grandchild, so a grandchild doesn't need anything special about the relationship itself to be in a protected category. What actually matters is the separate support test Part V applies to every child, grandchild included: was the deceased providing support, or under a legal obligation to provide it, immediately before death? No special showing that the grandparent "stood in a parent's place" is needed for the relationship itself to qualify.

The core question is still the one Part V asks of any claimed dependant: was the deceased providing support, or under a legal obligation to provide it, immediately before death? Occasional gifts or generosity from a grandparent generally won't be enough on their own. Because eligibility here turns heavily on the specific relationship and the quality of the evidence of dependency, a grandchild considering this kind of claim should get legal advice early to assess whether their situation is likely to meet the test.