diff -Nru massxpert3-10.4.3/debian/changelog massxpert3-10.4.3/debian/changelog
--- massxpert3-10.4.3/debian/changelog	2026-03-19 19:35:20.000000000 +0100
+++ massxpert3-10.4.3/debian/changelog	2026-04-14 12:18:52.000000000 +0200
@@ -1,3 +1,11 @@
+massxpert3 (10.4.3-1.1) unstable; urgency=medium
+
+  * Non-maintainer upload.
+  * Fixup breaks/replaces to make oldlibs packages installable
+    (Closes: #1132538, LP: #2148288)
+
+ -- Gianfranco Costamagna <locutusofborg@debian.org>  Tue, 14 Apr 2026 12:18:52 +0200
+
 massxpert3 (10.4.3-1) unstable; urgency=low
 
   * Fix bugs related to erroneous isotopic data files.
diff -Nru massxpert3-10.4.3/debian/control massxpert3-10.4.3/debian/control
--- massxpert3-10.4.3/debian/control	2026-03-19 19:35:20.000000000 +0100
+++ massxpert3-10.4.3/debian/control	2026-04-14 12:18:52.000000000 +0200
@@ -95,8 +95,8 @@
          ${misc:Depends},
          massxpert3-data (>= ${source:Upstream-Version})
 Suggests: massxpert3-doc (>= ${source:Upstream-Version})
-Replaces: massxpert, massxpert2
-Breaks: massxpert, massxpert2
+Replaces: massxpert, massxpert2 (<< 10.0.0-1)
+Breaks: massxpert, massxpert2 (<< 10.0.0-1)
 Description: polymer chemistry modelling and mass spectrometry data simulation (runtime)
  MassXpert3 allows the user to perform the following tasks:
  .
@@ -119,8 +119,8 @@
 Architecture: all
 Depends: ${misc:Depends},
 Suggests: massxpert3-doc (>= ${source:Upstream-Version})
-Replaces: massxpert2-data
-Breaks: massxpert2-data
+Replaces: massxpert2-data (<< 10.0.0-1)
+Breaks: massxpert2-data (<< 10.0.0-1)
 Description: polymer chemistry modelling and mass spectrometry data simulation (data)
  MassXpert3 allows the user to perform the following tasks:
  .
@@ -145,8 +145,8 @@
 Depends: libjs-jquery,
          libjs-highlight.js,
          ${misc:Depends}
-Replaces: massxpert2-doc
-Breaks: massxpert2-doc
+Replaces: massxpert2-doc (<< 10.0.0-1)
+Breaks: massxpert2-doc (<< 10.0.0-1)
 Description: polymer chemistry modelling and mass spectrometry data simulation (doc)
  MassXpert3 allows the user to perform the following tasks:
  .
diff -Nru massxpert3-10.4.3/debian/sid-control.txt massxpert3-10.4.3/debian/sid-control.txt
--- massxpert3-10.4.3/debian/sid-control.txt	2026-03-19 19:35:20.000000000 +0100
+++ massxpert3-10.4.3/debian/sid-control.txt	2026-04-14 12:18:52.000000000 +0200
@@ -95,8 +95,8 @@
          ${misc:Depends},
          massxpert3-data (>= ${source:Upstream-Version})
 Suggests: massxpert3-doc (>= ${source:Upstream-Version})
-Replaces: massxpert, massxpert2
-Breaks: massxpert, massxpert2
+Replaces: massxpert, massxpert2 (<< 10.0.0-1)
+Breaks: massxpert, massxpert2 (<< 10.0.0-1)
 Description: polymer chemistry modelling and mass spectrometry data simulation (runtime)
  MassXpert3 allows the user to perform the following tasks:
  .
@@ -119,8 +119,8 @@
 Architecture: all
 Depends: ${misc:Depends},
 Suggests: massxpert3-doc (>= ${source:Upstream-Version})
-Replaces: massxpert2-data
-Breaks: massxpert2-data
+Replaces: massxpert2-data (<< 10.0.0-1)
+Breaks: massxpert2-data (<< 10.0.0-1)
 Description: polymer chemistry modelling and mass spectrometry data simulation (data)
  MassXpert3 allows the user to perform the following tasks:
  .
@@ -145,8 +145,8 @@
 Depends: libjs-jquery,
          libjs-highlight.js,
          ${misc:Depends}
-Replaces: massxpert2-doc
-Breaks: massxpert2-doc
+Replaces: massxpert2-doc (<< 10.0.0-1)
+Breaks: massxpert2-doc (<< 10.0.0-1)
 Description: polymer chemistry modelling and mass spectrometry data simulation (doc)
  MassXpert3 allows the user to perform the following tasks:
  .