In Golfsoftware.com's League Manager, you can schedule your golfers to play exclusively within their flight/group.
First put Teams (players) that you want to play together, sequentially in your roster. (For example, teams 1-10 would play together and teams 11-20 would play together.)
On your main screen double-click the green TEAM line and give each team a group number. (In our example, teams 1-10 would be in Group #1. Teams 11-20 would be in Group #2.)
Click <Setup> on your toolbar; then select <Automatic Scheduling>.
Click the <Build/Optimize Schedule> button; then select the <ADVANCED Pairing Options> tab.
Check the options <Pair Matches Only within groups> AND <Put each group's matches in same teetime block>; then click <OK> to build your schedule.