diff --git a/SOAP/compression/make_virtual_snapshot.py b/SOAP/compression/make_virtual_snapshot.py
index ea30ea1c..6f2b673a 100644
--- a/SOAP/compression/make_virtual_snapshot.py
+++ b/SOAP/compression/make_virtual_snapshot.py
@@ -79,11 +79,43 @@ def make_virtual_snapshot(
     absolute_paths: If True, use absolute paths; if False, use relative paths
     """
 
-    # Copy the input virtual snapshot to the output
-    shutil.copyfile(snapshot, output_file)
+    # Check whether the input snapshot is a virtual file (distributed output)
+    # or a single file containing all the particle data (serial output)
+    with h5py.File(snapshot, "r") as infile:
+        is_virtual = infile["Header"].attrs.get("Virtual", [1])[0] == 1
 
-    # Open the output file
-    outfile = h5py.File(output_file, "r+")
+    if is_virtual:
+        # Copy the input virtual snapshot to the output
+        shutil.copyfile(snapshot, output_file)
+
+        # Open the output file
+        outfile = h5py.File(output_file, "r+")
+    else:
+        # Avoid copying the particle data by creating virtual datasets
+        # which link to the input snapshot
+        outfile = h5py.File(output_file, "w")
+        with h5py.File(snapshot, "r") as infile:
+            for k, v in infile.attrs.items():
+                outfile.attrs[k] = v
+            for name in infile:
+                # Keep soft links (e.g. GasParticles -> PartType0) as links
+                link = infile.get(name, getlink=True)
+                if isinstance(link, h5py.SoftLink):
+                    outfile[name] = h5py.SoftLink(link.path)
+                    continue
+                # Copy groups with metadata
+                if not name.startswith("PartType"):
+                    infile.copy(infile[name], outfile, name=name)
+                    continue
+                group = outfile.create_group(name)
+                for k, v in infile[name].attrs.items():
+                    group.attrs[k] = v
+                for dset_name, dset in infile[name].items():
+                    layout = h5py.VirtualLayout(shape=dset.shape, dtype=dset.dtype)
+                    layout[...] = h5py.VirtualSource(dset)
+                    vdset = group.create_virtual_dataset(dset_name, layout)
+                    for k, v in dset.attrs.items():
+                        vdset.attrs[k] = v
 
     # Calculate directories for path updates
     abs_snapshot_dir = os.path.abspath(os.path.dirname(snapshot))
@@ -198,6 +230,9 @@ def replace_path(old_path):
             else:
                 break
             file_nr += 1
+            # Serial output, so there is only a single auxiliary file
+            if "{file_nr}" not in auxiliary:
+                break
         if file_nr == 0:
             raise IOError(f"Failed to find files matching: {auxiliary}")
 
diff --git a/scripts/COLIBRE/compress_group_membership.sh b/scripts/COLIBRE/compress_group_membership.sh
index f04ec4c8..6a3c9eb9 100644
--- a/scripts/COLIBRE/compress_group_membership.sh
+++ b/scripts/COLIBRE/compress_group_membership.sh
@@ -55,7 +55,7 @@ sim="${SLURM_JOB_NAME}"
 inbase="${scratch_dir}/${sim}/SOAP_uncompressed/"
 
 # Location of the compressed output
-outbase="${output_dir}/${sim}/SOAP/"
+outbase="${output_dir}/${sim}/SOAP-HBT/"
 
 # Create the output folder if it does not exist
 outdir="${outbase}/membership_${snapnum}"
@@ -67,28 +67,39 @@ input_filename="${inbase}/membership_${snapnum}/membership_${snapnum}"
 # Compressed membership file basename
 output_filename="${outbase}/membership_${snapnum}/membership_${snapnum}"
 
-# Determine how many files we have
-nr_files=`ls -1 ${input_filename}.*.hdf5 | wc -l`
-nr_files_minus_one=$(( ${nr_files} - 1 ))
+# Determine how many chunk files we have
+if [[ -f ${input_filename}.0.hdf5 ]] ; then
+  nr_files=`ls -1 ${input_filename}.*.hdf5 | wc -l`
+else
+  nr_files=0
+fi
 
 # run h5repack in parallel using 32 processes on files 0 to 63
 # we could use more processes, but that causes a larger strain for the file
 # system and is therefore not really more efficient
 # make sure to update the 'seq' arguments when there are more/less membership
 # files
-echo Compressing ${nr_files} group membership files
-echo Source     : ${input_filename}
-echo Destination: ${output_filename}
-
-seq 0 ${nr_files_minus_one} | xargs -I {} -P 32 bash -c \
-  "h5repack -i ${input_filename}.{}.hdf5 -o ${output_filename}.{}.hdf5 -l CHUNK=10000 -f GZIP=4"
+echo "Source     : ${input_filename}"
+echo "Destination: ${output_filename}"
+
+if [[ ${nr_files} -eq 0 ]] ; then
+  # Serial output, so there is a single membership file
+  echo "Compressing single group membership file"
+  h5repack -i ${input_filename}.hdf5 -o ${output_filename}.hdf5 -l CHUNK=10000 -f GZIP=4
+  membership="${output_filename}.hdf5"
+else
+  echo "Compressing ${nr_files} group membership files"
+  nr_files_minus_one=$(( ${nr_files} - 1 ))
+  seq 0 ${nr_files_minus_one} | xargs -I {} -P 32 bash -c \
+    "h5repack -i ${input_filename}.{}.hdf5 -o ${output_filename}.{}.hdf5 -l CHUNK=10000 -f GZIP=4"
+  membership="${output_filename}.{file_nr}.hdf5"
+fi
 
 echo "Setting files to be read-only"
 chmod a=r "${output_filename}"*
 
 echo "Creating virtual snapshot"
 snapshot="${output_dir}/${sim}/snapshots/colibre_${snapnum}/colibre_${snapnum}.hdf5"
-membership="${output_filename}.{file_nr}.hdf5"
 virtual="${outbase}/colibre_with_SOAP_membership_${snapnum}.hdf5"
 python SOAP/compression/make_virtual_snapshot.py \
   --virtual-snapshot $snapshot \