江西省广昌县地名志，P226-227
According to the evidence, ⿱山畬 and ⿱山𤲞 has the meaning of 斜坡. They are congnate but have the different meaning of 畬.
In place names, 畬、畲 and 𤲞 can be used as each other. But there are not too many pairs.
As I know,
For radical 土, there are 𰊮（U+302AE）, ⿰土畲 and ⿰土𤲞;
For radical 山, there are ⿰山畬、⿰山𤲞、⿱山畬（WS2017）、⿱山𤲞.
However, 𤲞 is also a variant of 番 which means ⿰土𤲞 can be a variant of 墦, ⿰山𤲞 can be a variant of 嶓.
Considering people will more likely to think 余 and ⿱人米 as different characters, I suggest we encode them seperately.
New evidence
http://www.koreanhistory.or.kr/newchar/list_view.jsp?code=70922
I think here is a case that ⿰土𤲞 is a variant of a 墦 (坟)：
IRG Working Set 2021v3.0
Source: Xieyang WANG
Date: Generated on 2022-07-04
Unification
Evidence
According to the evidence, ⿱山畬 and ⿱山𤲞 has the meaning of 斜坡. They are congnate but have the different meaning of 畬.
In place names, 畬、畲 and 𤲞 can be used as each other. But there are not too many pairs.
As I know,
For radical 土, there are 𰊮（U+302AE）, ⿰土畲 and ⿰土𤲞;
For radical 山, there are ⿰山畬、⿰山𤲞、⿱山畬（WS2017）、⿱山𤲞.
However, 𤲞 is also a variant of 番 which means ⿰土𤲞 can be a variant of 墦, ⿰山𤲞 can be a variant of 嶓.
Considering people will more likely to think 余 and ⿱人米 as different characters, I suggest we encode them seperately.
I think here is a case that ⿰土𤲞 is a variant of a 墦 (坟)：
If experts think this to be unclear, I'd like to buy a hard copy and take a picture myself.