If you have G1/G0 and S phase values, you can calculate how much makes 100%. It is not the right way to do it, but it looks like you are out of other options. If you decide to do it this way, make it clear in M&M, how the G2/M numbers were calculated. Take it as a lesson illustrating importance of the raw data archiving. You should have the original files available for any results you publish.
You don't provide enough information. Presumably, the software is picking a model with diploid and tetraploid populations. If that is the case, there is probably a default value, since you can't know how much diploid G2+M and how much tetraploid G1 cells you have. The correct way to report it is 4C cells. You should have %G1dip, Sdip, 4C, Stet, G2+Mtet. A default value is based on some assumptions. Contact Verity to find out what they are.