If he were someone who was an assistant, with an ailing mother to support, well, it would be impossible.
( ( If ( he ( were ( someone ( who ( ( ( was ( an assistant ) ) , ) ( with ( an ( ailing ( mother ( to support ) ) ) ) ) ) ) ) ) ) ) ( , ( well ( , ( it ( ( would ( be impossible ) ) . ) ) ) ) ) )
(ROOT (S (SBAR (IN If) (S (NP (PRP he)) (VP (VBD were) (NP (NP (NN someone)) (SBAR (WHNP (WP who)) (S (VP (VBD was) (NP (DT an) (NN assistant)) (, ,) (PP (IN with) (NP (DT an) (VBG ailing) (NN mother) (S (VP (TO to) (VP (VB support))))))))))))) (, ,) (ADVP (RB well)) (, ,) (NP (PRP it)) (VP (MD would) (VP (VB be) (ADJP (JJ impossible)))) (. .)))
It would not be possible if he was an assistant with a sick mom. 
( It ( ( ( would not ) ( ( be possible ) ( if ( he ( was ( ( an assistant ) ( with ( a ( sick mom ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (MD would) (RB not) (VP (VB be) (ADJP (JJ possible)) (SBAR (IN if) (S (NP (PRP he)) (VP (VBD was) (NP (NP (DT an) (NN assistant)) (PP (IN with) (NP (DT a) (JJ sick) (NN mom))))))))) (. .)))