HashMap<Person, List<Package>> peopleToPackages = new HashMap<>();

    for (Package pk : packages) {
        if (pk.getCost() >= 5 ) {
            //use p1 (Daniel)
            List<Package> personsPkgList = peopleToPackages.get(p1);
            if (personsPkgList == null) {
                personsPkgList = new ArrayList<Package>();
            }
            personsPkgList.add(pk);
            peopleToPackages.put(p1, personsPkgList);
        } else {
            //use p2 (Tiffany)
            List<Package> personsPkgList = peopleToPackages.get(p2);
            if (personsPkgList == null) {
                personsPkgList = new ArrayList<Package>();
            }
            personsPkgList.add(pk);
            peopleToPackages.put(p2, personsPkgList);
        }

    }