I think it's just one sense. We probably should have 姉妹愛 as well.

@@ -14,3 +13,0 @@
-</sense>
-<sense>
-<pos>&n;</pos>
@@ -18 +14,0 @@
-<gloss>sibling love</gloss>

google image results show only (various forms 
of) literal 兄弟愛 (i.e. sense 2) which 
includes photos of brothers and sisters as 
well as just brothers. sense 2 should maybe 
lead. or maybe sense 1 should even be removed? 
it's not clear to me that it's used to refer 
to the non-literal "brotherly love". 
sekaidaihyakkajiten for example has this:
友愛という言葉は，狭くは〈友情friendship〉を意味する場
合もあるが，特に英語fraternityなど西欧語の訳語として，
兄弟の間の情愛から，さらにひろく家族など同一集団を結合す
る情愛，人間全体を一つの家族として包み込む人間相互の兄弟
愛をも意味する。このもっとも広い意味で，友愛は〈博愛
philanthropy〉〈隣人愛brotherly love〉と同義であ
る。… (友愛 entry)

chujiten has has 
"兄弟愛 <姉妹>
fraternal [sisterly] love"

兄妹愛	9897
兄弟愛	56498
姉弟愛	3918
姉妹愛	9413

daijs: 兄弟 "◆2・3は「兄妹」「姉弟」「姉妹」とも書
く。"
but 1 native informer in her mid- 30's said 
she wouldn't read 姉妹愛 as kyodaiai but 
shimaiai. she said of 兄妹愛 and 姉弟愛 she 
wasn't sure of the readings but wouldn't read 
them as きょうだいあい (i guess she'd resign to 
not read them at all!). this is just one 
informer though but if we wanted to include 
the other surface forms (which are fairly 
common, but I guess also fairly self-
explanatory) we should probably include the 
other readings, which might end up a little 
messy. we could also just add.a separate entry 
for 姉妹愛 and ignore the other 2 (like 
chujiten does)

@@ -14,0 +15,5 @@
+<sense>
+<pos>&n;</pos>
+<gloss>sibling affection</gloss>
+<gloss>sibling love</gloss>
+</sense>