  Two possible planetary nebulae (PN G035.5-00.4 and IRAS 18551+0159), one
newly re-identified supernova remnant (SNR G35.6-0.4), and one HII region
(G35.6-0.5) form a line-of-sight-overlapped complex known as G35.6-0.5. We
analyze 21 cm HI absorption spectra towards the complex to constrain their
kinematic distances. PN G035.5-00.4 has a distance from 3.8+/-0.4 kpc to
5.4+/-0.7 kpc. IRAS 18551+0159 is at 4.3+/-0.5 kpc. We discuss the distance for
SNR 35.6-0.4, for which the previous estimate was 10.5 kpc, and find plausible
for it to be 3.6+/-0.4 kpc. The new distance of SNR G35.6-0.4 and the derived
mass for the ~55 km/s CO molecular cloud can accommodate an association with
HESS J1858+020. We also conclude that SNR G35.6-0.4 is unlikely associated with
PSR J1857+0210 or PSR J1857+0212, which are projected into the SNR area.
