Train travel - portable baby/toddler seats?

[Saz67]

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.

How old ? Unless he/she can sit up you are a bit limited to using either an infant carrier( perhaps a polystrene one like \link{http://www.dooyoo.co.uk/child-car-seat/bettacare-cygnet-car-seat/\this althgouh not seen in stores for a while} ?), sling/front carrier or leave him in pushchair.

Would a sling not work? With a ring sling the baby can face forward and peek out like a kangaroo in a pouch, then lie down for naps / feeding etc. I would think he would be happier and calmer next to you, rather than sitting in a seat for 3 hours.