diff --git a/dlmo.mzn b/dlmo.mzn
index ae3a685..848cf92 100644
--- a/dlmo.mzn
+++ b/dlmo.mzn
@@ -30,15 +30,21 @@ array[Patient] of var bool: first_detected = [
 	| pt in Patient
 ];
 
-% --- Constraint ---
+enum Status = { First, ShiftBack, ShiftForward };
+array[Patient] of var Status: status;
 
+% --- Constraint ---
 % The DLMO should be detected on the second occasion (if not detected on the first occasion)
 constraint forall (pt in Patient) (
-	first_detected[pt] 
+	if status[pt] = First then
+		first_detected[pt] 
+	elseif status[pt] = ShiftBack then
 	% Before first occasion
-	\/ (critical_sample[pt] >= first_sample - (second_num_samples - 1) /\ critical_sample[pt] + 1 <= first_sample)
+		(critical_sample[pt] >= first_sample - (second_num_samples - 1) /\ critical_sample[pt] + 1 <= first_sample)
+	else
 	% After first occasion
-	\/ (critical_sample[pt] >= first_sample + (first_num_samples - 1) /\ critical_sample[pt] + 1 <= first_sample + (first_num_samples - 1) + (second_num_samples - 1))
+		(critical_sample[pt] >= first_sample + (first_num_samples - 1) /\ critical_sample[pt] + 1 <= first_sample + (first_num_samples - 1) + (second_num_samples - 1))
+	endif
 );
 
 % --- Objective ---
@@ -46,7 +52,8 @@ solve minimize
 	% Number of tests on first occasion
 	(length(Patient) * first_num_samples)
 	% Number of test on second occasion
-	+ (count(pt in Patient) (not first_detected[pt]) * second_num_samples);
+	+ (count(pt in Patient) (status[pt] = ShiftBack) * min(second_num_samples, first_sample - min(Horizon) + 1))
+	+ (count(pt in Patient) (status[pt] = ShiftForward) * min(second_num_samples, max(Horizon) - (first_sample + (first_num_samples -1) + 1)));
 
 % --- Output ---