diff --git a/Elwig/Helpers/Billing/BillingData.cs b/Elwig/Helpers/Billing/BillingData.cs
index 8f63888..dbd1372 100644
--- a/Elwig/Helpers/Billing/BillingData.cs
+++ b/Elwig/Helpers/Billing/BillingData.cs
@@ -306,7 +306,8 @@ namespace Elwig.Helpers.Billing {
                     if ((ks.Count > vaributes.Count() * 0.5 && useDefault) || ks.Count == vaributes.Count()) {
                         foreach (var k in ks) {
                             if (!(originalData[$"{k[..2]}/"]?.AsValue().TryGetValue<string>(out var o) ?? false) || o == v)
-                                data.Remove(k);
+                                if (!(originalData[k.Split('-')[0]]?.AsValue().TryGetValue<string>(out var o2) ?? false) || o2 == v)
+                                    data.Remove(k);
                         }
                         data["default"] = v;
                         CollapsePaymentData(data, originalData, vaributes, useDefault);
@@ -317,7 +318,8 @@ namespace Elwig.Helpers.Billing {
                     if ((ks.Count > vaributes.Count() * 0.5 && useDefault) || ks.Count == vaributes.Count()) {
                         foreach (var k in ks) {
                             if (!(originalData[$"{k[..2]}/"]?.AsValue().TryGetValue<decimal>(out var o) ?? false) || o == v)
-                                data.Remove(k);
+                                if (!(originalData[k.Split('-')[0]]?.AsValue().TryGetValue<decimal>(out var o2) ?? false) || o2 == v)
+                                    data.Remove(k);
                         }
                         data["default"] = v;
                         CollapsePaymentData(data, originalData, vaributes, useDefault);
@@ -371,6 +373,15 @@ namespace Elwig.Helpers.Billing {
                 } else if (k.Contains("/-")) {
                     data.Remove(k, out var val);
                     data.Add(k.Replace("/-", "-"), val);
+                    if (k[0] == '/' || k.Contains('-')) {
+                        foreach (var (k2, o) in originalData) {
+                            if (!data.ContainsKey(k2) && k2.Contains('-') && k2.Contains("-" + k.Split('-')[1]) && !k2.Contains("/-")
+                                && (!k2.Contains('/') || k2.Length <= 4 || !data.ContainsKey(k2[2..])))
+                            {
+                                data[k2] = o?.DeepClone();
+                            }
+                        }
+                    }
                 }
             }
 
diff --git a/Tests/HelperTests/BillingDataTest.cs b/Tests/HelperTests/BillingDataTest.cs
index 3fb11df..6db2c25 100644
--- a/Tests/HelperTests/BillingDataTest.cs
+++ b/Tests/HelperTests/BillingDataTest.cs
@@ -972,5 +972,67 @@ namespace Tests.HelperTests {
                 }
                 """));
         }
+
+        private static IEnumerable<List<T>> GetPermutations<T>(T[] input) {
+            if (input.Length <= 1)
+                yield return [..input];
+            for (int i = 0; i < input.Length; i++) {
+                yield return [input[i]];
+                foreach (var p in GetPermutations(input.Where((_, j) => j != i).ToArray())) {
+                    p.Insert(0, input[i]);
+                    yield return p;
+                }
+            }
+        }
+
+        private static IEnumerable<List<HashSet<RawVaribute>>> GetCurves(RawVaribute[] vaributes, int minNumCurves = 1, int maxNumCurves = 10) {
+            foreach (var p in GetPermutations(vaributes)) {
+                for (int nCurves = minNumCurves; nCurves <= Math.Min(maxNumCurves, p.Count); nCurves++) {
+                    yield return Enumerable.Range(0, nCurves)
+                        .Select(n => p.Where((v, idx) => idx % nCurves == n).ToHashSet())
+                        .ToList();
+                }
+            }
+        }
+
+        private readonly HashSet<string> TestedCurves = [];
+
+        private void TestCollapse(List<HashSet<RawVaribute>> curves) {
+            var str = string.Join("\n", curves.Select(c => string.Join("  ", c.Select(v => v.ToString().PadRight(6)).Order())).Order().Select((c, n) => $"{n + 1}: [ " + c + " ]"));
+            if (!TestedCurves.Add(str))
+                return;
+            var vaributes = curves.SelectMany(v => v).ToList();
+            List<GraphEntry> entries = curves
+                .Select((l, n) => new GraphEntry(n, 4, new BillingData.Curve(BillingData.CurveMode.Oe, new() {
+                    [73] = n + 1,
+                }, null), GetSelection(l.Select(v => v.ToString()))))
+                .ToList();
+            var data = BillingData.FromGraphEntries(entries);
+            var test = PaymentBillingData.FromJson(data.ToJsonString(), vaributes);
+            for (int i = 0; i < curves.Count; i++) {
+                foreach (var v in curves[i]) {
+                    var val = test.CalculatePrice(v.SortId!, v.AttrId, v.CultId, "QUW", false, 73.0, 15.0);
+                    var actualCurve = (int)val;
+                    Assert.That(actualCurve, Is.EqualTo(i + 1), $"Invalid: {v} (Curve {i + 1} -> {actualCurve})\n\n{str}\n\n{data.ToJsonString(JsonOpts)}\n");
+                }
+            }
+        }
+
+        [Test]
+        public void TestCollapse_01_Permutations() {
+            RawVaribute[][] configurations = [
+                [new("GV/-"), new("WR/-"), new("ZW/-"), new("GV/K-"), new("WR/K-"), new("ZW/K-")],
+                [new("GV/-"), new("WR/-"), new("GV/K-"), new("WR/K-"), new("GV/S-"), new("WR/S-")],
+                [new("GV/-"), new("WR/-"), new("ZW/-"), new("GV/-B"), new("WR/-B"), new("ZW/-B")],
+                [new("GV/-"), new("WR/-"), new("GV/-B"), new("WR/-B"), new("GV/-KIP"), new("WR/-KIP")],
+                [new("GV/-"), new("GV/K-"), new("ZW/-"), new("ZW/K-"), new("GV/-B"), new("GV/K-B"), new("ZW/-B"), new("ZW/K-B")],
+            ];
+            Assert.Multiple(() => {
+                foreach (var config in configurations) {
+                    foreach (var c in GetCurves(config))
+                        TestCollapse(c);
+                }
+            });
+        }
     }
 }