The fact that Sinn Féin leader Mary Lou McDonald TD addressed Plaid Cymru's conference and Michelle O'Neill MLA, Leader in the Northern Ireland Assembly, will be took in a panel discussion. has non seemed to sent Plaid's opponents and the UK media into apoplexy speaks volumes about the peace process and why we must not let Brexit destroy the Good Friday Agreement.
Plaid Cymru leader Adam Price AM said both parties shared a "common vision of our respective nations playing a central role in Europe's future."
Mr Price has invited all pro-Remain parties in Ireland to attend the conference.
The SNP's Alyn Smith MEP, President of the European Free Alliance group and First Vice-President of the Greens/EFA Group in the European Parliament, will also be a speaking guest at the conference.
Plaid Cymru leader Adam Price AM said:
"As the UK government pursues its policy of a hard Brexit that will devastate our economies and communities, it is imperative that the alliance between the parties of Remain is stronger than ever before.
"Because of the sacrifice of people on both sides, it is crucial that the peace process and the Good Friday Agreement is protected.
"Wales and Ireland have a very strong historical bond and I look forward to working with all pro-Remain parties in Northern Ireland as we try to avoid a disastrous crash out Brexit."
Speaking ahead of her conference address, Mary Lou McDonald TD said:
"I look forward to addressing the conference and meeting the delegates. Brexit represents a fundamental challenge to our economy, our agreements and rights of citizens.
"It has the potential to undermine the progress that we have achieved since the signing of the Good Friday Agreement. It is important that all of those who oppose Brexit stand together in the common cause."
In her speech Sinn Féin president Mary Lou McDonald has warned the UK Prime Minister that Ireland would not be bullied over Brexit
The Dublin politician called for a “pan-Celtic political culture to defeat Toryism” in her keynote address on Saturday.
She also criticised the Prime Minister for his Brexit plan - saying what Boris Johnson presented as a “good solution” to the border was “far from it”.
If Boris Johnson cannot put forward proposals that maintain the guarantees in the backstop, then the ultimate solution of Irish unity should be put on the table.– MARY LOU MCDONALD, SINN FÉIN
Mr Johnson has said his plan, which would see Northern Ireland remain tied to EU single market rules for trade in goods while leaving the customs union with the rest of the UK, represented a “fair and reasonable compromise”.
However the European Commission put a halt to any weekend discussions, saying the proposals "do not provide a basis for concluding an agreement."
The DUP supports Mr Johnson's plan which includes giving Stormont a veto on any future arrangements. The Irish premier, Taoiseach Leo Varadkar has expressed concern over the potential return of customs controls.
The Prime Minister wants to get an agreement in place for the EU summit on 17 October, paving the way for the UK to leave with a deal at the end of the month
As Sinn Féin, who has Isaid supported a Remain vote, abstain from their seats in the House of Commons, and the DUP supported a Leave vote,Independent MP Sylvia Hermon is the only MP representing Northern Ireland who sits in the House of Commons who supported Remain. Hermon described the potential for a "no deal" Brexit as a "threat to UK stability", saying that such a circumstance could lead to a hard border, which could then, combined with changing demographics in Northern Ireland, lead to a border poll on united Ireland, which could lead to Northern Ireland unifying with the Republic of Ireland.
Plaid Cymru should be applauded for welcoming Sinn Féin,to its conference not only as a fellow Remain party and fellow "Nationalist" but also as a recognition of its major role in the peace process .
A Process that the DUP who Incidentally did not support the Good Friday Agreement a process that along with its fellow unionist in the British Government , they seem intent on destroying.