Reindexed the sentences.

Splitting out.

@@ -7,3 +6,0 @@
-</r_ele>
-<r_ele>
-<reb>ですら</reb>

Examples from DIJG:
通勤に便利でさえあればどんなところでもいいんです。
Any location will be fine as long as it is convenient for commuting.
アメリカ人でさえあれば雇ってもらえる。
The only thing you need in order to be hired is to be American.

I agree with Marcus. Also, they're not always interchangeable; すら can't be used in conditional clauses.
No idea where "but; however" came from. Dropping that sense.
We might want a sense for the usage given above.

@@ -11,0 +12 @@
+<pos>&exp;</pos>
@@ -14,2 +15 @@
-<xref type="see" seq="1008460">でも・2</xref>
-<gloss>even</gloss>
+<gloss>even (e.g. even a child)</gloss>
@@ -17,0 +18 @@
+<pos>&exp;</pos>
@@ -19,3 +20,5 @@
-<xref type="see" seq="1008460">でも・1</xref>
-<gloss>but</gloss>
-<gloss>however</gloss>
+<xref type="see" seq="1005120">さえ・2</xref>
+<s_inf>after a noun or na-adjective; in conditional clauses</s_inf>
+<gloss>as long as (it is, you are, etc.)</gloss>
+<gloss>(if) only</gloss>
+<gloss>just</gloss>

It might make sense to pair them together in a 
book on grammar but as a dictionary, I think 
different words should be in different 
entries.

Because they are different words/expressions, 
not different pronunciations of the same word 
or different readings of the same kanji. They 
might mean the same thing/be used in the same 
way but they're still not the same word.