One problem that crops up now and then concerns how to include more than one bridi within a NU clause. An example is my translation of Deuteronomy 8:12~14, which I have rendered:
.i tezu'ebo rivbi va'o lo nu do mo'u citka jebo cu tolxagji je cu zbasu lo zabna zdani je cu xabju ri
ju'ei loi cagda'u be do ferti se panzi ju'ei loi rijno joi loi solji vu'o po do zei'a sormei ju'ei loi ro se ponse be do zei'asai sormei kei
lo nu lo menli be do co'a se'ijgi ju'ei do tolmo'i tu'a la .iauex. ku noi cevni do je noi vimcu do la .misr. ku no'u le tutra pe lo ka bapse'u
(note, uses simplified connectives, the experimental tag {zei'a} which is basically {fi'o te zenba}: {zei'a sormei} means "increasingly many" / "to increase in number", and {ju'ei}, which shall be discussed. Yes, I'm pretty terrible with abusing experimental constructs.)
There are several solutions:
official-Lojban solution #1: use {ju'e ... gi ...}. Requires forethought, and only takes two bridi. Chaining them to allow more is impractical.
official-Lojban solution #2: close each NU clause then join it to a new abstractor sumti. e.g. {lo nu broda kei jo'u lo nu brode}. Pretty wordy.
experimental-grammar solution #1: {ju'ei}; essentially acts like a tight-scope {.i} that doesn't close sub-clauses. {lo nu broda ju'ei brode}. Has the advantage of not requiring forethought, but has the disadvantage of not automatically closing any bridi tails; if one of your abstraction-bridi happens to contain a lot of nested NU or POI, they must be closed manually.
experimental-grammar solution #2: Allow {tu'e...tu'u} to act as a single bridi in NU clauses: {lo nu tu'e broda .i brode tu'u}. Does require forethought, but gives a new "level zero" for {.i} to automatically reset to until closed by {tu'u}.
And bonus official-Lojban solution #3, with an experimental shorthand that doesn't require new grammar: {tu'a la'e lu broda .i brode li'u}, with {tu'ai} (selma'o LU) being shorthand for {tu'a la'e lu}. Useful, but may be semantically vague, given lack of LO NU qualification, and {tu'a} possibly implying missing information.
Bonus problem: A related problem is how to make several sentences share a sumtcita-term. e.g: *{ca lo nu mi stuvi'e le sralygu'e kei tu'e lo zabna cu fasnu .i lo mabla cu fasnu tu'u}. {ju'e...gi} also works here, but retains the chaining problem, while I don't know if any of the other listed solutions work.