Evidence of family members remaining in your home country whilst you travel怎么证明?

给爸妈签探亲,什么文件符合这个要求呀 Evidence of family members remaining in your home country whilst you travel
我是独生子女,户口本上就是我和父母三个人。他俩一起来英国,难道要提供我爷爷奶奶的证件?
谢谢指教!

无视就行,这不是必须要求