For Cycle 18, we have implemented the following changes to APT for preparing Proposals:
1) APT 17.4.3 has an option to specify a Cycle 18 Multi Cycle Treasury Proposal.
2) As of APT 17.4, support for the Hubble Legacy Archive footprint service has been added to the Aladin tool in APT. Select File>Open in Aladin and then choose the HLA from the left hand column of Image Servers.