It’s also not entirely clear to me how block overflow is handled. Do you have a second guarantor waiting in the wings for the second block?
If you have overflow, that means you have more than the amount of the first block coming in, so you only need the guarantor for the last block. E.g. if people enter with $150,000 collectively, then $100,000 of that goes to pay out for the first block (which will definitely pay out because all of its numbers are allocated). In the 50% chance that the second block is won, then the guarantor will add $50,000 to pay out the second block (and otherwise the guarantor will allocate the funds, basically the guarantor is just committing to take all the unclaimed tickets on the last block).
If you have overflow, that means you have more than the amount of the first block coming in, so you only need the guarantor for the last block. E.g. if people enter with $150,000 collectively, then $100,000 of that goes to pay out for the first block (which will definitely pay out because all of its numbers are allocated). In the 50% chance that the second block is won, then the guarantor will add $50,000 to pay out the second block (and otherwise the guarantor will allocate the funds, basically the guarantor is just committing to take all the unclaimed tickets on the last block).