There are a number of different holds. The two most common are the double football hold, and the double cradle hold where the infant places his/her legs on top of the toddler's body. And based upon these two there are variations where the toddler can be football hold and the infant in a cradle hold or vise verse. Some people are even brave enough to use the cross-cradle hold, but I get worried about kicking the younger baby. Here are some diagrams intended for twins, but can be modified for a newborn and an older child.
Kellymom is also a great resource for suggestions on how to handle criticism. I'm stealing some of their ideas.
1) Educate- When my friend started asking questions about weaning, I started explaining basic nursing biology. This is the technique that I use most often since I tend to be logical. However, this may back fire because someone could think your being a "know-it-all" so if you know the person well enough to know this won't work, don't use it.
2) Quote an Authority- "Well my pediatrician says (the AAP says...the WHO says)...." sometimes will normalize what's going on and take the edge off of sounding preachy.
3) Laugh it off- This I can't really pull off. It's not in my personality to joke about something that I view as serious, but some people can use this. Like the comment about nursing until age 7, I could have laughed off by saying "Oh, sure, I can follow him to grade school and make sure he nurses during lunch."
4) Ignore- If you view what's going on as going to cause a firestorm, sometimes it's good to just let it go. You can give a short answer like yes or no and act distracted or change the subject entirely. Going to the bathroom helps or playing with your child. Some people call this the bean dip method.
5) Respond to the source of concern- If you know the person well enough, sometimes the reason why they say what they say is out of concern for you or your child. Like in the case of nursing while pregnant, you can reassure the person that you are getting enough calories, drinking plenty of fluids, and getting lots of rest. Then you can say your doctor says that you and your unborn are fine. Sometimes people have odd ways of looking for reassurance and aren't trying to intentionally hurt your feelings.
6) If the person won't let things go- you've tried every tactic and this issue keeps coming up, then simply tell them that you appreciate their input but this is what works for your family and you don't want to wish to discuss it further. And shorten it at every objection (an old teaching tactic). So it would look something like this.
"I appreciate your concern, but we're doing what works best for our family. I do not wish to discuss this subject further."
" Again, I appreciate your concern, but we're doing what's works best for us." or "We're doing what works best for us. I do not wish to discuss this further."
"We're doing what works best for us." or "I do not wish to discuss this further."
And if they still persist, then simply leave the room. They haven't got the idea.
Sometimes people wish to change your mind about tandem nursing or breastfeeding while pregnant (bwp) by using the "wear em' down method." Be aware of this especially among relatives and stand by your decision by avoiding the discussion. Some relatives are operating on misinformation, and it's been my experience that it's really hard to dispel old wives tales.
Also be aware that sometimes criticism comes from a place of hurt. When I started researching breastfeeding during pregnancy, my mom kept giving me comments like "well, it might not work for you" and the like. I'm sure she felt like I was giving her flack for formula feeding and I'm sure she was worried that I would be disappointed if things didn't work out. I ignored the comments and instead talked about all the knowledge I was gaining. In the end, things did work out and so her worries ended.
I believe the same thing is happening from my critical friend. She has twins and had difficulties nursing let alone tandem nursing. I believe that she feels a bit of regret that she had to turn to pumping and bottles. She did the best that she could, and she shouldn't feel like she failed anyone. Her concerns come from a place of experience even though my situation is different. As I explained HB can latch himself on without any help. His younger brother may have problems, but that's one child and not two. So I understand her concern about tandem nursing and why she thinks nursing while pregnant is strange (I don't know of anyone personally other than myself who has done so). That's why I don't take it as insulting but as an opportunity to change the way society views a woman's body.