abstractors with SE and connectives
You can use se with abstractors. Most common is sedu'u, but others are possible. The abstractors that have x2 places are ni, jei, li'i, si'o, du'u, pu'o, zu'o. The abstractors that have only x1 are nu, ka, za'i, mu'e.
mi cusku le sedu'u mi ze'e noroi srere si srera
You can use connectives with abstractors. From the Book, chapter 11, section 13:
le ka je ni la frank. ciska cu xlali
But you cannot freely use them together! se jei broda parses as se (jei broda), and se jei je ni broda parses as se (jei je ni broda). The se applies to both abstractors. se is ungrammatical inside the connected abstractors.
jei je seni broda - bzzt! ungrammatical
(On the other hand, it's perfectly legal to do excessive negation: jeinai najenai ninai na broda. Ow, I think I just burned out some brain cells!)
Keep in mind that ka has an unofficial x2: The thing that bears the quality in question. Hence:
le ka ce'u sutra
le ka ce'u sutra kei be le mi gerku
My dog's speed