The Prophet salla Allahu alaihi wa sallam used to order people before every prayer to straighten the lines and narrow the gaps. You should tell them this or send a paper to the Imam so that he would bring the issue to their attention during the khutba.

I visited a mosque for Jumu’ah prayers and while praying I noticed that the women were not covering the lines but forming new lines (saf) while the elderly women who sat on the chairs were also not in line but had their own line at the backI know that its not right and that lines must be covered but I need your explanation on this so next Friday I can go and explain this to them.