You can reload multiple times and often that will get you the results you seek, however as one of the definitions of insanity is to keep repeating the same action(s) and hoping for a different result, you might consider changing some variables. No guarantee it work, especially since I have zero clue as to how the behind scenes 'Flow Logic' occurs, but sometimes the day of the week and time of day matter.
What I mean is, if you have a save on say a Tuesday morning and continue to reload said save hoping for a different result and you never get the result you want, try on a different day at a different time. The stats don't always have to be maxed, you can try stat levels of say 90%. Is Jessica and/or Heather busy with another job? i.e. if Jessica is the maid, she'll never be on the beach until afternoon thus missing any morning occurrence of her and Heather both being available.
To me, Holiday Island is like a giant puzzle and although frustrating at times, the solution is there. Finding it is half the fun, but again that's just my opinion.