Nearlythree - thanks for that, your plan seems kinder than most I've heard of.
Tonight was the first night, dd I put back 4 times, she cried herself to sleep, after only 10 minutes at 10pm then ds after a further ten minutes started to cry, but it was a frightened sob cry from the belly, I weakened and stroked his brow to get him to sleep ten minutes later, so I think we did ok 35 minutes total.
Will try your method with ds tomorrow, twins both reacted so differently! but better than expected (although night is still young) dd accepted placing back in bed, I think she just cried to let us know she wasn't happy about the change, but ds it was upsetting to hear him cry like that, so it may work out harder having different procedures once they link up to what each other doing.
Maybe easier to get them to sleep staggered times, oh well, will cross that bridge, if and when it happens! but very happy with tonites results, so far!