You're right; I didn't notice the 《沿》 etc. in Daijirin. 
Seems a good approach.

希望に沿う	30842
希望に添う	40934

Daijr restricts the senses by kanji and I don't see any overlap between 沿う and 添う/副う.
Meikyo has this helpful note on its 添う/副う entry: "4は、付き従う意に重点を置くときは「沿う」とも書くが、一般には「添う」でまかなう。「副」は1,4に使うが、まれ。" "4" and "1" in this note correspond to senses 1 and 2 respectively on our 添う entry.
I'm seeing nothing that suggests 副う is used with the senses we have for 沿う.
Based on Meikyo's note (confirmed by n-gram counts), the only amendment I suggest is adding sense 1 from 添う to this entry.

@@ -26 +25,0 @@
-<xref type="see" seq="1440810">添う・1</xref>
@@ -30,0 +30,10 @@
+<sense>
+<pos>&v5u;</pos>
+<pos>&vi;</pos>
+<xref type="see" seq="1440810">添う・1</xref>
+<s_inf>also written 添う</s_inf>
+<gloss>to meet (wishes, expectations, etc.)</gloss>
+<gloss>to satisfy</gloss>
+<gloss>to comply with</gloss>
+<gloss>to live up to</gloss>
+</sense>

沿う	359900
添う	96488
副う	6426
Daijr and Koj combine these 3 in the one entry.
GG5: 沿う with glosses much like here. 添う & 副うcombined, again much like here.
中辞典 and Grand Concise: Just 沿う and 添う in separate entries.
ルミナス: Combines 沿う and 添う (1) go along; walk along (2) meet, satisfy
Unidic: combines all 3, treating 添う and 副う as alternative surface forms of 沿う.

I noticed this when parsing some text with 副う and saw Unidic pointed to 沿う. In fact our gloss for 添う/副う worked better. Should we follow the kokugos? Or stay with our GG5-like split?

gg5, prog

Tightening x-ref.

@@ -17,0 +18 @@
+<pos>&vi;</pos>
@@ -19,0 +21 @@
+<gloss>to stick to (a line)</gloss>
@@ -23,2 +25,3 @@
-<xref type="see" seq="1440810">添う</xref>
-<gloss>to follow (a plan, etc.)</gloss>
+<pos>&vi;</pos>
+<xref type="see" seq="1440810">添う・1</xref>
+<gloss>to follow (a policy, plan, etc.)</gloss>
@@ -25,0 +29 @@
+<gloss>to align with</gloss>