If, within the 30-day period specified in Section 66451.14, the owner does not file a request for a hearing in accordance with Section 66451.16, the local agency may, at any time thereafter, make a determination that the affected parcels are to be merged or are not to be merged. A determination of merger shall be recorded as provided for in Section 66451.12 no later than 90 days following the mailing of notice required by Section 66451.13.
Source:
Section 66451.17, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=GOV§ionNum=66451.17..