Grace endured several almost unimaginable losses within the time span of just over a year. Aside from the loss of Joe, Thomas MacDonagh, her brother-in-law, and many of her friends were also executed for leadership roles in the Rising. In August 1917, her sister, Muriel, (Thomas MacDonagh's widow) drowned, leaving two small children. One month later, Grace's father died.

Grace continued her career as an artist, eventually becoming quite successful. She used her talents to promote Sinn Fein policies and earned her living as a commercial illustrator. Grace was elected to the executive of Sinn Fein in 1917 and continued to support the struggles for Irish independence her entire life. Many Sinn Fein members were also involved in the Volunteers and the Irish Republican Brotherhood, and their separatist policies become more accepted after the Rising. Sinn Fein candidates, including Count George Plunkett, Joe's father, won three elections to the Parliament in 1917.

In 1919, Grace published a book of her political cartoons entitled To Hold as Twere.

Grace and her sisters were strongly opposed to the Treaty of 1921, which divided Ireland into the Republic of Ireland and British-ruled Northern Ireland. Grace wrote letters to several publications stating that the republic proclaimed by the signers of the Proclamation of the Irish Republic in 1916 was a reality that should be honoured by all Irish people.

In an article entitled "The White Flag of 1916", published in Poblacht na h-Éireann Vol.1 No.12 March 15, 1922, Grace wrote:

I am far from thinking that all those who are in support of the Treaty are necessarily dishonest. Far from it. Some of them are merely those who, after the long, exhausting period in the wilderness of error, have temporarily lost the strength of soul that took them through it - the strength that proved their nobility again and again. Now, in the natural reaction after the rigours of that 'forty days', they are brought by a temper up to a huge mountain and offered a kingdom at a price.

Christ choose hunger rather than make a disgraceful contract with the devil. That the Treatists in their innermost hearts think the Treaty disgusting (and the Oath that binds them, or ought to bind them if oaths are to be taken seriously, to the Free State only, and not to a future Republic) is proved by their repeated assertions that they mean to break that Oath, and work on for the Republic.

That is the point - the price to be paid. Ireland must pause and think before she pays it. The woman, who in desperate circumstances, accepts comfortable conditions at the price of her honour, has many good material arguments to back up her decision. Having more money, she can then assist others in their distress, give employment, perhaps, and get, for the first time, 'the right to live her own life'.

Who, with any practical sense, would reject the substance for the shadow? A few hasty words read by a Priest, a blessing that cannot be grasped in the hand, and is less tangible than air - are these absurdities to stand in the way of her chance of 'living her own life'?

So say the Treatists regarding Oaths. This being so, and the Government of Ireland being for the present in their hands, one is forced to ask: What is to be the national standard? Is honour to have a place in national life?

Ireland today stands in the position of the woman about to barter her honour. Do intangible things matter? Or must we as a country aim only for things that can be grasped in the hand? Our national soul must answer 'Yes' or 'No'. If the value of intangible things is denied, why stop anywhere?

Let us break our vows of marriage and our pledged words in other directions, when nothing tangible, no arm of the law can keep us to them. Let us shut the churches and drive God from the place of honour he holds in the land.

Joseph Plunkett marching with the white flag, surrendered but only his body. He gave his life rather than take a shameful Oath of Allegiance to the Empire. That he could have saved his life at this cost is certain.

England always knew it would pay better to have Ireland contented on her terms; and no doubt the men who laid down their lives in Easter Week could have got 'terms of agreement' had they mentioned them. General Smuts in South Africa, got them readily in like circumstances.

But Joseph Plunkett knew what those terms would be, and forebore to negotiate. As he loved Ireland enough to lay down his life for her, it will be admitted that he loved her enough to wish to see her at peace. But he made no offers, like [General] Smuts, to take the easy road, knowing the penalties.

In 1923, during the Irish Civil War, Grace (along with many other republicans) spent three months in Kilmainham Gaol (Jail) because of suspected subversive activities against the Free State government.

Finding work as an artist was difficult in the depressed Irish economy after the Civil War, and Grace quite often lived in impoverished surroundings. She continued doing commercial art and cartoons, eventually developing a larger audience and several sponsors. Her book of theatre sketches, Twelve Nights at the Abbey Theatre and a second book of her cartoons received very positive public response and enthusiastic acknowledgment of her talents among her peers. By 1930, Grace was firmly established as an important member of Dublin's cultural community.

Grace is described as being very stylish, generous, outgoing and having a "mercurial" wit. She could occasionally become temperamental, which is understandable when considering all that she had lived through. She was very devoted to her several nieces and nephews, and spent much of her time with family. Grace also enjoyed the company of friends and the many cultural events that her beloved Dublin had to offer.