Monobore expansion system - anchored liner

Methods for forming a wellbore may include placing an upper section of inside a lower section of a parent liner; positioning an upper sealing member and a lower sealing member in the wellbore to form a pressure chamber, and expanding the second liner using the pressure chamber. The sealing members move axially relative to one another and the second liner has an inner bore that is hydraulically isolated from the pressure chamber. A related apparatus may include upper and lower sealing members that cooperate to form a pressure chamber that is hydraulically isolated from an inner bore of the second liner. A work string may include the sealing members, a connector that extends through the pressure chamber and the second liner; and an expander. The expander expands the second liner in response to the axial separation of the sealing members.