2 parts passion fruit juice (such as Welch's®)
2 parts guava nectar (such as Goya®)
1 part fresh squeezed orange juice
Optional: Malibu Rum
Optional: Pineapple mint as a garnish
Combine passion fruit juice, guava nectar, and orange juice in a large glass pitcher and stir well. Chill until ready to serve.
The ratios are a guideline and should be adjusted to taste. Some folks start with a 1:1:1 ratio as OJ is the least expensive ingredient.
Cook Real Hawaii has a ratio of 3.25 cups guava nectar, 2.75 cups passion fruit juice (or nectar), and 1.5 cups fresh orange juice.
If you can't find nectar, then the frozen passion fruit I happen to have in my freezer says 1 bag (14 oz) to 40 oz water and sugar to taste will make passion fruit juice, and I imagine guava nectar would be the same ratio.
You could probably calculate it, but this is largely a matter of taste, so start roughly there and adjust as necessary.