First-off, apply the concepts of Excess and Surplus to the undivided SFR improved parcel. For the OP, in addition to that SFR improved parcel, there are 2 other separate properties. The SFR improved parcel is "the property"; apply your analysis for Excess or Surplus (if either are present) to "the property". This, I understand, you will argue with. I offer these words for others who are following this string.
I agree with this - (mostly ) if you read my posts they say the same thing. ( the essence of the problem ) I disagreed with a few others you statements you made. But this above can mislead some who seem confused about what they are engaged to appraise (imo )
Cleary, yes, an appraiser applies the analysis of any extra parcels as to whether they are excess or surplus to " the property" ( the SF improved parcel ). ( yes, and my posts say the same )
However, the "property" that is the subject of the appraisal, is the SFR improved parcel TOGETHER as a PACKAGE /ASSEMBLAGE with an excess lot or lots . ( surplus lot is not the topic, here )
The Yes/No choice question for HBU as improved on page one of a URAR is : is the HBU as improved /yes or no, for the PACKAGE /ASSEMBLAGE ( above ) I say URAR because that is the form in most of these assignments -
The URAR form is NOT asking what is the HBU of a vacant lot or vacant lots . An appraiser might develop an opinon of HBU for the lot or an estimate of value for it as part of the development, but the HBU of the lot or lot alone is NOT what the URAR form asks for on page one, nor does it ask the HBU of the subject on its primary lot ( though that also might be developed as part of assignment )
To eliminate confusion: the HBU question on page one of the URAR is for the identified property which is the subject of assignment ( the property : improvement on a parcel along with excess lot/lots. )