surrogate

surrogate adjective [ always before noun ] uk/ˈsʌrəɡɪt/ us
used instead of someone or something else

заменяющий
Twenty years older than her, he effectively became a surrogate father. surrogate noun [ C ]
someone or something that is used instead of someone or something else

замена, заменитель
He seemed to regard her as a surrogate for his dead mother.