How to add more qubits to a pre-defined quantum circuit in Qiskit?

I have a pre-defined quantum circuit with n initial qubits. I want to add m more qubits to it during the calculation as ancillary qubits. How can I do that?

You can add 2 quantum circuits with +. Below is an example of adding 1 ancillary qubit to the 'data' quantum circuit:

# Define 'data' circuit
qr1 = QuantumRegister(2,'data')
qc1 = QuantumCircuit(qr1)

# Operations on 'data' qubits
qc1.h(0)
qc1.cx(0,1)

# Define an ancillary qubit
qr2 = QuantumRegister(1, 'ancillary')
qc2 = QuantumCircuit(qr2)

# Add the ancillary qubit to the 'data' circuit
q_tot = qc1 + qc2

q_tot.draw('mpl')