diff --git a/ereuse_devicehub/resources/proof/models.py b/ereuse_devicehub/resources/proof/models.py
index 3fe4ab7b..13b81cc9 100644
--- a/ereuse_devicehub/resources/proof/models.py
+++ b/ereuse_devicehub/resources/proof/models.py
@@ -26,6 +26,7 @@ from teal.resource import url_for_resource
 from ereuse_devicehub.db import db
 from ereuse_devicehub.resources.action.models import Action, DisposeProduct, \
     EraseBasic, Rate, Trade
+from ereuse_devicehub.resources.device.models import Device
 from ereuse_devicehub.resources.models import Thing
 
 
@@ -43,6 +44,11 @@ class Proof(Thing):
     id = Column(UUID(as_uuid=True), primary_key=True, default=uuid4)
     type = Column(Unicode, nullable=False)
     ethereum_hash = Column(CIText(), default='', nullable=False)
+    devices = relationship(Device,
+                           backref=backref('proofs_multiple', lazy=True),
+                           secondary=lambda: ProofDevice.__table__,
+                           order_by=lambda: Device.id,
+                           collection_class=OrderedSet)
 
     @property
     def url(self) -> urlutils.URL:
@@ -74,6 +80,13 @@ class Proof(Thing):
         return '<{0.t} {0.id} >'.format(self)
 
 
+
+class ProofDevice(db.Model):
+    device_id = Column(BigInteger, ForeignKey(Device.id), primary_key=True)
+    proof_id = Column(UUID(as_uuid=True), ForeignKey(Proof.id),
+                      primary_key=True)
+
+
 class ProofTransfer(JoinedTableMixin, Proof):
     transfer_id = Column(UUID, ForeignKey(Trade.id), nullable=False)
     transfer = relationship(DisposeProduct,
diff --git a/ereuse_devicehub/resources/proof/schemas.py b/ereuse_devicehub/resources/proof/schemas.py
index aa7cba1c..16a833b7 100644
--- a/ereuse_devicehub/resources/proof/schemas.py
+++ b/ereuse_devicehub/resources/proof/schemas.py
@@ -11,6 +11,7 @@ from ereuse_devicehub.resources.proof import models as m
 from ereuse_devicehub.resources.models import STR_BIG_SIZE, STR_SIZE
 from ereuse_devicehub.resources.schemas import Thing
 from ereuse_devicehub.resources.action import schemas as s_action
+from ereuse_devicehub.resources.device import schemas as s_device
 
 
 class Proof(Thing):
@@ -19,6 +20,12 @@ class Proof(Thing):
     ethereum_hash = SanitizedStr(default='', validate=Length(max=STR_BIG_SIZE),
                                    data_key="ethereumHash", required=True)
     url = URL(dump_only=True, description=m.Proof.url.__doc__)
+    devices = NestedOn(s_device.Device,
+                       many=True,
+                       required=True,  # todo test ensuring len(devices) >= 1
+                       only_query='id',
+                       data_key='deviceIDs',
+                       collection_class=OrderedSet)
 
 
 class ProofTransfer(Proof):
diff --git a/ereuse_devicehub/resources/proof/views.py b/ereuse_devicehub/resources/proof/views.py
index c645479d..cf63bdfe 100644
--- a/ereuse_devicehub/resources/proof/views.py
+++ b/ereuse_devicehub/resources/proof/views.py
@@ -33,8 +33,8 @@ class ProofView(View):
                 Model = db.Model._decl_class_registry.data[prf['type']]()
                 proof = Model(**p)
                 db.session.add(proof)
+                db.session.commit()
                 proofs.append(self.schema.dump(proof))
-            db.session.commit()
             response = jsonify({
                 'items': proofs,
                 'url': request.path