So this gets to what I was discussing.
Arcane research paper (http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0116046#s2) but here is what it shows...
Closest correlation in voting between M5S and SEL which includes PD "dissidents". (close correlation of PD/FI reflecting their coalition government, FI own center-right dissidents Alternativa Popolare now Civica Popolare formally within PD electoral bloc)

So re-inclusion of PD-dissidents now component in SEL would not hugely shift policy of M5S-PD coalition as
M5S already votes closest to SEL, while re-integrating those dissidents would re-enforce PD weight in coalition.
(and increase the persuasion of their political stance to M5S, re: negotiations for policy)
Charts unfortunately don't distinguish ex-PD dissidents from other components of SEL.
OFC besides not being necessary for majority, that runs contra to maintenance of Renzi policy without Renzi.

In other news, Lega announced openness to M5S coalition which is other majority scenario if PD refuses.

Five Starts leader Di Maio announced agreement with Lega for earliest possible elections on July 8,
refusing technical or all-party government which would govern while delaying elections to December or later.
http://www.ansa.it/english/news/politics/2018/05/07/july-8-election-if-no-govt-deal-2_1c4c9a15-c996-4844-9d86-e89dea43be82.html
The earliest possible election IMHO implies likelyhood of not modifying election laws, which was theory mentioned by some here.

Acting leader Martina of centrist Democratic party has pushed for negotiations with Five Stars,
albeit has been rebuffed so far by Renzi wing of party, thus forced to forswear that option before new elections.
https://www.politico.eu/article/italys-politicians-5star-movement-democratic-party-get-one-last-chance-to-strike-a-deal/
But fact he became leader at all despite his distance on this issue (which was apparent immediately after election)
suggests the policy on non-cooperation with Five Stars is less fixed than Renzi would prefer to have it.

In relation to previous post with graph, I think interesting point is that NCD/AP (ex-Forza who allied with PD)
could be seen as exemplar of those in PD who would most oppose cooperation with Five Stars, based on voting pattern.
Of course, AP collapsed and 2/3 of it ended up within Forza-Lega coalition, so perhaps problematic as core of PD policy.

I tried to post earlier, but the site wouldn't let me... trying again now...

Earlier, Berluconi announced Forza would accept a Lega coalition with Five Stars,
although they wouldn't vote for it their votes aren't needed to do so AFAIK.
A Five Star-Lega government may rely on other parties for judicial appointments etc. (?)

Berlusconi just won a court ruling saying he should now be allowed to run for office.
Although if the coalition government goes thru, there may not be elections soon.
The ruling could also be appealed and possibly reversed, who knows.

I guess they have a government now? 5-Stars and Lega formed a coalition.

https://www.express.co.uk/news/world/967715/Italy-latest-Lega-and-Five-Star-agree-coalition-deal

GIUSEPPE Conte has accepted the role of Italian Prime Minister after the country's populist parties finally agreed a coalition deal.