Hi, any suggestions for portable seats that can be used with inflexible and high backed train seats? Can't use an infant carrier/car seat as it won't fit the ultralight pushchair I need for slogging about on public transport. Need to keep my 5 month old DS safe while I care for my 2 older step children on train journeys of 3+ hours. This train travel pattern will continue for years, so a seat with shelf life at DS grows would be very useful. Many thanks.