Glossary entry (derived from question below)
English term or phrase:
multiball
Portuguese translation:
bolas suplementares
English term
Portugal
Translator and Terminologist
Native in: Portuguese 
Works in: English to Portuguese, French to Portuguese, Spanish to Portuguese
multiball
The multiball system in football permits a match immediately to resume with another ball when the original match ball goes out of play.
https://alloutfootball.co.uk/faq/what-is-multi-ball-in-footb...
Para português europeu. Obrigada.
Proposed translations
Portugal
Expert EN/SP to PT-PT Translator
Native in: Portuguese (Variant: European/Portugal)
Works in: English to Portuguese, Spanish to Portuguese, Portuguese, and 2 more.
bolas suplementares
Podem ser colocadas bolas suplementares em redor do terreno de jogo para serem
utilizadas no decorrer do jogo, desde que satisfaçam as exigências estipuladas na Lei
2 e que a sua utilização seja controlada pelo árbitro."
https://www.fpf.pt/pt/DownloadDocument.ashx?id=16881
| Obrigada, Cláudia! |
bolas adicionais
| Obrigada, ferreirac! |
Brazil
English-Portuguese; Spanish-Portuguese
Native in: Portuguese (Variants: Brazilian, European/Portugal) 
Works in: English to Portuguese, Spanish to Portuguese, Italian to Portuguese, and 1 more.
Bolas múltiplas / bolas extras
| Obrigada, William! |
sistema multibolas
No tênis de mesa tem, não achei para futebol - mas sugiro o mesmo termo
| Obrigada,Clauwolf! |
Brazil
20+ y/exp Translation
Native in: Portuguese (Variant: Brazilian)
Works in: English to Portuguese, German to Portuguese, Spanish to Portuguese
reposição de bola em jogo
reposição de bola em jogo por equipa de apanha-bolas
| Obrigada, Bartira! |
Brazil
32 years engineering/law/contracts
Native in: English (Variant: US) , Portuguese (Variant: Brazilian)
Works in: English to Portuguese, Portuguese to English
bolas para reposição (em jogo)
| Obrigada, Mário! |
Discussion
"Eight replacement match balls placed around the pitch on a cone alongside a Ball Assistant".