diff --git a/py/LSS/SV3/altmtltools.py b/py/LSS/SV3/altmtltools.py
index 77af6de7f..59c3b86f8 100755
--- a/py/LSS/SV3/altmtltools.py
+++ b/py/LSS/SV3/altmtltools.py
@@ -691,12 +691,10 @@ def makeTileTracker(altmtldir, survey = 'main', obscon = 'DARK', startDate = Non
     archiveDates = []
     
     for tileid in TilesSel:
-        print('tileid = {0}'.format(tileid))
         
         ts = str(tileid).zfill(6)
         
         thisTileMTLDT = MTLDT[MTLDT['TILEID'] == tileid]
-        
         # 20260302 LGN Rewriting to remove ARCHIVEDATE check. 
         # 20260302 LGN We want fa actions before the endDate to be included.
         if len(thisTileMTLDT) == 0:
@@ -713,12 +711,31 @@ def makeTileTracker(altmtldir, survey = 'main', obscon = 'DARK', startDate = Non
         thisFAFN = FABaseDir + f'/{ts[0:3]}/fiberassign-{ts}.fits'
 
         thisfhtOrig = fitsio.read_header(thisFAFN)
-        thisfadate = thisfhtOrig['MTLTIME']
+
+        # 20260909 LGN: In order to fix the MTLTIME ordering bug: github.com/desihub/fiberassign/issues/517
+        # We now need to get the fa action timestamp manually, this requires finding the final entry from
+        # the same program (1B inclusive) that occured before the tiles NOWTIME.
+        # Code adapted from: https://github.com/desihub/fiberassign/blob/48a0e6a7361c1230ae48d9fb55fe08fae6594ae6/py/fiberassign/fba_launch_io.py
+        if obscon.upper() in ["DARK1B","BRIGHT1B"]:
+            d = MTLDT.copy(copy_data=True)
+            if obscon.upper() == "DARK1B":
+                keep = np.isin(d["PROGRAM"], ["DARK", "DARK1B"])
+            elif obscon.upper() == "BRIGHT1B":
+                keep = np.isin(d["PROGRAM"], ["BRIGHT", "BRIGHT1B"])
+        
+            keep &= d["TIMESTAMP"] < thisfhtOrig['NOWTIME']
+            
+            # AR taking the latest timestamp
+            thisfadate = np.unique(d[keep]["TIMESTAMP"])[-1]
+        # If a standard DARK/BRIGHT tile there's no timing issue, revert to original behavior
+        else:
+            thisfadate = thisfhtOrig['MTLTIME']
+    
         thisfadate = desitarget.mtl.add_to_iso_date(thisfadate, 1)
         thisfanite = int(''.join(thisfadate.split('T')[0].split('-')))
         if thisfanite > endDate:
             continue
-        
+
         TileIDs.append(tileid)
         TypeOfActions.append('fa')
         TimesOfActions.append(thisfadate)
@@ -775,7 +792,8 @@ def makeTileTracker(altmtldir, survey = 'main', obscon = 'DARK', startDate = Non
         TimesOfActions.append('2025-07-21T23:36:04+00:00')
         doneFlag.append(False)
         archiveDates.append(20250721)
-    else:
+    elif (obscon.lower() == 'dark') and (max(TimesOfActions) > '2025-07-21T23:36:04+00:00'):
+        log.info(f'Obscon = {obscon} but lya1b = {lya1b}')
         log.info('NOT adding QSO NUMOBS Increase Action')
         log.info('You will not mimic real survey decisions after 2025-07-21T23:36:04+00:00')
 
diff --git a/py/LSS/SV3/fatools.py b/py/LSS/SV3/fatools.py
index bc723b1c5..5c29b7f7d 100755
--- a/py/LSS/SV3/fatools.py
+++ b/py/LSS/SV3/fatools.py
@@ -23,6 +23,9 @@
 from desitarget.mtl import inflate_ledger
 from desiutil.log import get_logger
 
+# fiberassign
+from fiberassign.utils import get_whether_to_reorder_mtl, get_whether_to_use_np_concatenate
+
 log = get_logger()
 
 
@@ -595,6 +598,22 @@ def altcreate_mtl(
         if 'dark1b' in mtldir or 'bright1b' in mtldir:
             log.info('Running with maketwostyle=True')
             is_ext = True
+
+            # 20260909 LGN: Adding new handling here for the BRIGHT1B order bug: https://github.com/desihub/fiberassign/pull/512
+            # this requires getting the tile rundate, I'm grabbing it from the fiberassign header (matching makeTileTracker)
+            ts = str(tileIDs[0])
+            thisFAFN = os.path.join(os.getenv("DESI_ROOT"),'target','fiberassign','tiles','trunk', f'{ts[0:3]}', f'fiberassign-{ts}.fits')
+            thisfhtOrig = fitsio.read_header(thisFAFN)
+            tile_rundate = thisfhtOrig['RUNDATE']
+
+            # use the rundate to get extra argument values, set and pass to read_targets_in_tiles
+            reorder_mtl = get_whether_to_reorder_mtl(tile_rundate)
+            use_np_concatenate = get_whether_to_use_np_concatenate(tile_rundate)
+
+            extra_args = {}
+            extra_args["reorder"] = reorder_mtl
+            extra_args["use_concatenate"] = use_np_concatenate
+            
             # LGN Formatting the path to bright or dark ledgers
             # LGN Passing list of directories to read_targets_in_tiles
             mtldir_short = os.path.join(
@@ -611,7 +630,8 @@ def altcreate_mtl(
                 isodate=mtltime,
                 verbose=verbose,
                 tabform='ascii.ecsv',
-                maketwostyle = is_ext
+                maketwostyle = is_ext,
+                **extra_args
             )
         
         else: