Can't receive group texts from iPhone users

[hotdice99]

This topic is questioned frequently but I can't find a similar situation. I have a Galaxy S4 with Android 5.0.1. This is not about me changing from an iPhone to an Android. Both my siblings are iPhone users. Lately, I can't receive group messages from my siblings unless they turn off iMessenger. But when they turn off iMessenger, they then cannot receive texts from their children (yes, we are adults who don't know technology very well). I use the Messaging app and Group Conversation is checked. If they turn off iMessenger, texts come through as MMS. We can text individually just fine. I'll take any suggestions.
Turned the phone off? - yes
Cleared the cache? - yes
Tried another message app? - no; don't want to unless it is an ultimate

 

[the tall guy]

Hi, if you are part of a group, then when the Iphone user sends a message it is recognizing the other sender has an Iphone and is sending an Imessage - hence why you are not receiving the message.

It would be better if you could get everyone to download Whatsapp - that way it's a cross platform app that works great for group chats.