Sim, parece que seria permitido.

“I’m half and half,’ said Seamus. ‘Me dad’s a Muggle. Mam didn’t tell him she was a witch ’til after they were married. Bit of a nasty shock for him.”
_{^{- Harry Potter and the Philosopher's Stone, Chapter 7 (The Sorting Hat)}}

Trouxas que têm permissão para saber sobre magia parecem ter permissão para vê-la sendo usada e interagir com itens mágicos, como Justin Finch-Fletchley fez sua mãe trouxa ler os livros de Lockhart.

“My name was down for Eton, you know, I can’t tell you how glad I am I came here instead. Of course, mother was slightly disappointed, but since I made her read Lockhart’s books I think she’s begun to see how useful it’ll be to have a fully trained wizard in the family …”
_{^{- Harry Potter and the Chamber of Secrets, Chapter 6 (Gilderoy Lockhart)}}

Os livros de Lockhart são obviamente mágicos, já que as fotos dele em suas capas se movem, e o conteúdo seria sobre magia.

“Written across it in fancy gold letters were the words: Gilderoy Lockhart’s Guide to Household Pests. There was a big photograph on the front of a very good-looking wizard with wavy blond hair and bright blue eyes. As always in the wizarding world, the photograph was moving; the wizard, who Harry supposed was Gilderoy Lockhart, kept winking cheekily up at them all.”
_{^{- Harry Potter and the Chamber of Secrets, Chapter 3 (The Burrow)}}

Os Grangers, ambos trouxas, tiveram permissão para entrar em Flourish and Blotts, uma livraria bruxa onde é provável que eles testemunhem magia.

“They each grabbed a copy of Break with a Banshee, and sneaked up the line to where the rest of the Weasleys were standing with Mr and Mrs Granger.”
_{^{- Harry Potter and the Chamber of Secrets, Chapter 4 (At Flourish and Blotts)}}

Como eles são permitidos em lugares exclusivamente para assistentes, onde outros usariam mágica, é quase certo que os cônjuges trouxas de assistentes podem ver seus cônjuges ou filhos usarem magia. Os Dursleys testemunham as pessoas usando magia várias vezes, incluindo magos que conhecem as leis, como o Sr. Weasley.

“Fred scrambled around, cramming them back into his pocket, then gave the Dursleys a cheery wave, stepped forward and walked right into the fire, saying, ‘The Burrow!’ Aunt Petunia gave a little shuddering gasp. There was a whooshing sound, and Fred vanished.

‘Right then, George,’ said Mr Weasley, ‘you and the trunk.’

Harry helped George carry the trunk forward into the flames, and turn it onto its end so that he could hold it better. Then, with a second whoosh, George had cried, ‘The Burrow!’ and vanished too.”
_{^{- Harry Potter and the Goblet of Fire, Chapter 4 (Back to the Burrow)}}

Dumbledore também usa magia na frente dos Dursleys.

“Vernon Dursley had entered the room, Petunia at his shoulder and Dudley skulking behind them both.

‘Yes,’ said Dumbledore simply, ‘I shall.’ He drew his wand so rapidly that Harry barely saw it; with a casual flick, the sofa zoomed forwards and knocked the knees out from under all three of the Dursleys so that they collapsed upon it in a heap. Another flick of the wand and the sofa zoomed back to its original position.”
_{^{- Harry Potter and the Half-Blood Prince, Chapter 3 (Will and Won’t)}}

Embora ele esteja fazendo isso para se divertir, é improvável que ele o faça se for realmente proibido pelo Ministério.

“Harry looked round; all three of the Dursleys were cowering with their arms over their heads as their glasses bounced up and down on their skulls, the contents flying everywhere.

‘Oh, I’m so sorry,’ said Dumbledore politely, and he raised his wand again. All three glasses vanished. ‘But it would have been better manners to drink it, you know.”
_{^{- Harry Potter and the Half-Blood Prince, Chapter 3 (Will and Won’t)}}

O mais provável é que seja permitido.

Se pensarmos sobre isso, o perigo de usar magia na frente dos muggles é devido ao risco de expor a comunidade do assistente. Enquanto o trouxa já estiver ciente da magia, das habilidades do parceiro e da criança, eu acho que é seguro assumir que tais magos têm permissão para fazer mágica na frente de seus significantes (ou outros membros não mágicos da família).

Por exemplo, a família de Lily (e mais tarde a família de Petúnia) eram trouxas e Lily abertamente fez mágica na frente deles. A família Dursley também sabia das origens de Harry e o único erro quando ele fazia magia parecia ser justificado por ele ser proibido de fazer mágica fora de Hogwarts como um bruxo menor de idade.

Harry Potter e a Câmara Secreta:

Dear Mr. Potter, We have received intelligence that a Hover Charm was used at your place of residence this evening at twelve minutes past nine. As you know, underage wizards are not permitted to perform spells outside school, and further spellwork on your part may lead to expulsion from said school (Decree for the Reasonable Restriction of Underage Sorcery, 1875, Paragraph C).