Another option is somewhat more complex but doable, I saw it in a HX4 mission
1) have a plan trigger where the opfor assaults the position (pace=run, Move ROE=run, path = single path element on the position), but don't assign it
2) have a flag ("action"), set it to true every time anyone dies
3) have a time elapsed event that checks the flag, redirects to another block ("charge") if its false, and sets the flag false if it was true (i.e. redirectif(not(getFlagState) group charge ), next response would be setFlag to false)
4) in the "charge" call a loop teams in company
5) in the loop call abort the team's current plan and assign the plan mentioned in #1
Now if a certain amount of time passes with no deaths, they assault.
Obviously you can add other conditions in the time elapsed event to better suit your mission