diff --git a/src/miner.h b/src/miner.h
--- a/src/miner.h
+++ b/src/miner.h
@@ -50,6 +50,34 @@
         : tx(_tx), txFee(_fees), txSize(_size), txSigOps(_sigOps),
           packageOrder(0), packageFee(_fees), packageSize(_size),
           packageSigOps(_sigOps) {}
+
+    /**
+     * Calculate the feerate for this transaction.  Use the minimum of the
+     * package feerate, or the transaction itself.  Parents TXNs should never
+     * end up "paying for" child transactions.
+     */
+    CFeeRate FeeRate() const {
+        // In order to avoid numerical errors, we reorder to use multiplication
+        // instead of vision.
+        return int64_t(txSize) * packageFee < int64_t(packageSize) * txFee
+                   ? CFeeRate(packageFee, packageSize)
+                   : CFeeRate(txFee, txSize);
+    }
+
+private:
+    /**
+     * Include a parent transactions accounting into our own.
+     * We assume that this is used in topological order by BlockAssembler.
+     */
+    void AccountForParent(const CBlockTemplateEntry &parent) {
+        packageOrder = std::max(parent.packageOrder + 1, packageOrder);
+        packageFee += parent.packageFee;
+        packageSize += parent.packageSize;
+        packageSigOps += parent.packageSigOps;
+    }
+
+    friend class BlockAssembler;
+    friend struct CBlockTemplateEntryTest;
 };
 
 struct CBlockTemplate {
diff --git a/src/test/miner_tests.cpp b/src/test/miner_tests.cpp
--- a/src/test/miner_tests.cpp
+++ b/src/test/miner_tests.cpp
@@ -28,6 +28,13 @@
 
 #include <memory>
 
+struct CBlockTemplateEntryTest {
+    static void AccountForParent(CBlockTemplateEntry &e,
+                                 const CBlockTemplateEntry &p) {
+        return e.AccountForParent(p);
+    }
+};
+
 BOOST_FIXTURE_TEST_SUITE(miner_tests, TestingSetup)
 
 static CFeeRate blockMinFeeRate = CFeeRate(DEFAULT_BLOCK_MIN_TX_FEE_PER_KB);
@@ -781,6 +788,15 @@
     BOOST_CHECK_EQUAL(txEntry.packageFee, 1 * SATOSHI);
     BOOST_CHECK_EQUAL(txEntry.packageSize, 200);
     BOOST_CHECK_EQUAL(txEntry.packageSigOps, 10);
+
+    CBlockTemplateEntry txChildEntry(txRef, 10 * SATOSHI, 2000, 20);
+    CBlockTemplateEntryTest::AccountForParent(txChildEntry, txEntry);
+    BOOST_CHECK_EQUAL(txChildEntry.txFee, 10 * SATOSHI);
+    BOOST_CHECK_EQUAL(txChildEntry.txSize, 2000);
+    BOOST_CHECK_EQUAL(txChildEntry.txSigOps, 20);
+    BOOST_CHECK_EQUAL(txChildEntry.packageFee, 11 * SATOSHI);
+    BOOST_CHECK_EQUAL(txChildEntry.packageSize, 2200);
+    BOOST_CHECK_EQUAL(txChildEntry.packageSigOps, 30);
 }
 
 BOOST_AUTO_TEST_SUITE_END()