小朋友在百貨公司意外趺親撞穿頭

You are entitled to do whatever they want.

So the answer is yes.

However, due to lack of information, it is difficult to tell your chance of success. On that basis, it does not seem you have a chance.

佢有冇放兒童不宜提示牌？冇就有得諗。

冇
百貨公司冇責任同你湊小朋友 所以你冇權claim百貨公司
除非你搵到証明小朋友既傷係關百貨公司某D原因 例如地滑等等
如果要追究邊個疏忽 我諗應該係小朋友個家長而唔係百貨公司